diff --git a/other/java/client/src/main/proto/filer.proto b/other/java/client/src/main/proto/filer.proto
index feb37fbd7f..2a21f1e947 100644
--- a/other/java/client/src/main/proto/filer.proto
+++ b/other/java/client/src/main/proto/filer.proto
@@ -359,6 +359,8 @@ message ObjectMutation {
     bool touch_mtime = 12;                 // PATCH_EXTENDED: set the entry's Mtime to now (e.g. a metadata-replace copy)
     bool remove_empty_parent = 13;         // DELETE: also remove the parent directory when the delete leaves it empty (best-effort)
     bool keep_remote_object = 14;          // DELETE: leave the object on the mounted remote storage
+    WriteCondition condition = 15;         // optional precondition checked under the transaction lock just before this mutation applies
+    string condition_key = 16;             // entry the condition evaluates against; empty = the mutation's target
 }
 
 // Recompute re-derives a pointer entry (directory/name on the mutation) from the
@@ -404,6 +406,7 @@ message ObjectTransactionRequest {
 message ObjectTransactionResponse {
     string error = 1;
     FilerError error_code = 2;
+    optional int32 failed_mutation = 3;  // index of the mutation that failed (its condition or its apply); unset when the request-level condition failed
 }
 
 // PosixLockRange is one advisory byte-range lock. Owner identity is (sid, owner):
diff --git a/weed/pb/filer.proto b/weed/pb/filer.proto
index feb37fbd7f..dd1d6edb05 100644
--- a/weed/pb/filer.proto
+++ b/weed/pb/filer.proto
@@ -359,6 +359,8 @@ message ObjectMutation {
     bool touch_mtime = 12;                 // PATCH_EXTENDED: set the entry's Mtime to now (e.g. a metadata-replace copy)
     bool remove_empty_parent = 13;         // DELETE: also remove the parent directory when the delete leaves it empty (best-effort)
     bool keep_remote_object = 14;          // DELETE: leave the object on the mounted remote storage
+    WriteCondition condition = 15;         // optional precondition checked under the transaction lock just before this mutation applies
+    string condition_key = 16;             // entry the condition evaluates against; empty = the mutation's target
 }
 
 // Recompute re-derives a pointer entry (directory/name on the mutation) from the
@@ -399,11 +401,13 @@ message ObjectTransactionRequest {
     bool is_moved = 8;                 // set on a forwarded transaction so the receiver applies it locally instead of forwarding again
     string request_id = 9;             // idempotency token: the owner records the outcome and replays it on a retried request instead of re-applying
     string condition_alt_key = 10;     // if the condition's entry is absent, evaluate it against this entry instead (e.g. null slot, else latest version)
+    bool condition_prefer_alt = 11;    // evaluate condition_alt_key (the latest version) first; fall back to the primary entry only when the alt path cannot resolve
 }
 
 message ObjectTransactionResponse {
     string error = 1;
     FilerError error_code = 2;
+    optional int32 failed_mutation = 3;  // index of the mutation that failed (its condition or its apply); unset when the request-level condition failed
 }
 
 // PosixLockRange is one advisory byte-range lock. Owner identity is (sid, owner):
diff --git a/weed/pb/filer_pb/filer.pb.go b/weed/pb/filer_pb/filer.pb.go
index cb5f44b2b5..e4efbf7528 100644
--- a/weed/pb/filer_pb/filer.pb.go
+++ b/weed/pb/filer_pb/filer.pb.go
@@ -1561,6 +1561,8 @@ type ObjectMutation struct {
 	TouchMtime        bool                   `protobuf:"varint,12,opt,name=touch_mtime,json=touchMtime,proto3" json:"touch_mtime,omitempty"`                                                                            // PATCH_EXTENDED: set the entry's Mtime to now (e.g. a metadata-replace copy)
 	RemoveEmptyParent bool                   `protobuf:"varint,13,opt,name=remove_empty_parent,json=removeEmptyParent,proto3" json:"remove_empty_parent,omitempty"`                                                     // DELETE: also remove the parent directory when the delete leaves it empty (best-effort)
 	KeepRemoteObject  bool                   `protobuf:"varint,14,opt,name=keep_remote_object,json=keepRemoteObject,proto3" json:"keep_remote_object,omitempty"`                                                        // DELETE: leave the object on the mounted remote storage
+	Condition         *WriteCondition        `protobuf:"bytes,15,opt,name=condition,proto3" json:"condition,omitempty"`                                                                                                 // optional precondition checked under the transaction lock just before this mutation applies
+	ConditionKey      string                 `protobuf:"bytes,16,opt,name=condition_key,json=conditionKey,proto3" json:"condition_key,omitempty"`                                                                       // entry the condition evaluates against; empty = the mutation's target
 	unknownFields     protoimpl.UnknownFields
 	sizeCache         protoimpl.SizeCache
 }
@@ -1693,6 +1695,20 @@ func (x *ObjectMutation) GetKeepRemoteObject() bool {
 	return false
 }
 
+func (x *ObjectMutation) GetCondition() *WriteCondition {
+	if x != nil {
+		return x.Condition
+	}
+	return nil
+}
+
+func (x *ObjectMutation) GetConditionKey() string {
+	if x != nil {
+		return x.ConditionKey
+	}
+	return ""
+}
+
 // Recompute re-derives a pointer entry (directory/name on the mutation) from the
 // current contents of a scanned directory, atomically under the transaction's
 // lock. It is mechanical: the filer picks the child that sorts first or last by
@@ -1830,11 +1846,12 @@ type ObjectTransactionRequest struct {
 	Mutations          []*ObjectMutation      `protobuf:"bytes,3,rep,name=mutations,proto3" json:"mutations,omitempty"`
 	IsFromOtherCluster bool                   `protobuf:"varint,4,opt,name=is_from_other_cluster,json=isFromOtherCluster,proto3" json:"is_from_other_cluster,omitempty"`
 	Signatures         []int32                `protobuf:"varint,5,rep,packed,name=signatures,proto3" json:"signatures,omitempty"`
-	ConditionKey       string                 `protobuf:"bytes,6,opt,name=condition_key,json=conditionKey,proto3" json:"condition_key,omitempty"`             // if set, evaluate the condition against this entry instead of lock_key (still locking lock_key)
-	RouteKey           string                 `protobuf:"bytes,7,opt,name=route_key,json=routeKey,proto3" json:"route_key,omitempty"`                         // ring key identifying the owner filer; a non-owner forwards the whole transaction to it
-	IsMoved            bool                   `protobuf:"varint,8,opt,name=is_moved,json=isMoved,proto3" json:"is_moved,omitempty"`                           // set on a forwarded transaction so the receiver applies it locally instead of forwarding again
-	RequestId          string                 `protobuf:"bytes,9,opt,name=request_id,json=requestId,proto3" json:"request_id,omitempty"`                      // idempotency token: the owner records the outcome and replays it on a retried request instead of re-applying
-	ConditionAltKey    string                 `protobuf:"bytes,10,opt,name=condition_alt_key,json=conditionAltKey,proto3" json:"condition_alt_key,omitempty"` // if the condition's entry is absent, evaluate it against this entry instead (e.g. null slot, else latest version)
+	ConditionKey       string                 `protobuf:"bytes,6,opt,name=condition_key,json=conditionKey,proto3" json:"condition_key,omitempty"`                       // if set, evaluate the condition against this entry instead of lock_key (still locking lock_key)
+	RouteKey           string                 `protobuf:"bytes,7,opt,name=route_key,json=routeKey,proto3" json:"route_key,omitempty"`                                   // ring key identifying the owner filer; a non-owner forwards the whole transaction to it
+	IsMoved            bool                   `protobuf:"varint,8,opt,name=is_moved,json=isMoved,proto3" json:"is_moved,omitempty"`                                     // set on a forwarded transaction so the receiver applies it locally instead of forwarding again
+	RequestId          string                 `protobuf:"bytes,9,opt,name=request_id,json=requestId,proto3" json:"request_id,omitempty"`                                // idempotency token: the owner records the outcome and replays it on a retried request instead of re-applying
+	ConditionAltKey    string                 `protobuf:"bytes,10,opt,name=condition_alt_key,json=conditionAltKey,proto3" json:"condition_alt_key,omitempty"`           // if the condition's entry is absent, evaluate it against this entry instead (e.g. null slot, else latest version)
+	ConditionPreferAlt bool                   `protobuf:"varint,11,opt,name=condition_prefer_alt,json=conditionPreferAlt,proto3" json:"condition_prefer_alt,omitempty"` // evaluate condition_alt_key (the latest version) first; fall back to the primary entry only when the alt path cannot resolve
 	unknownFields      protoimpl.UnknownFields
 	sizeCache          protoimpl.SizeCache
 }
@@ -1939,12 +1956,20 @@ func (x *ObjectTransactionRequest) GetConditionAltKey() string {
 	return ""
 }
 
+func (x *ObjectTransactionRequest) GetConditionPreferAlt() bool {
+	if x != nil {
+		return x.ConditionPreferAlt
+	}
+	return false
+}
+
 type ObjectTransactionResponse struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	Error         string                 `protobuf:"bytes,1,opt,name=error,proto3" json:"error,omitempty"`
-	ErrorCode     FilerError             `protobuf:"varint,2,opt,name=error_code,json=errorCode,proto3,enum=filer_pb.FilerError" json:"error_code,omitempty"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
+	state          protoimpl.MessageState `protogen:"open.v1"`
+	Error          string                 `protobuf:"bytes,1,opt,name=error,proto3" json:"error,omitempty"`
+	ErrorCode      FilerError             `protobuf:"varint,2,opt,name=error_code,json=errorCode,proto3,enum=filer_pb.FilerError" json:"error_code,omitempty"`
+	FailedMutation *int32                 `protobuf:"varint,3,opt,name=failed_mutation,json=failedMutation,proto3,oneof" json:"failed_mutation,omitempty"` // index of the mutation that failed (its condition or its apply); unset when the request-level condition failed
+	unknownFields  protoimpl.UnknownFields
+	sizeCache      protoimpl.SizeCache
 }
 
 func (x *ObjectTransactionResponse) Reset() {
@@ -1991,6 +2016,13 @@ func (x *ObjectTransactionResponse) GetErrorCode() FilerError {
 	return FilerError_OK
 }
 
+func (x *ObjectTransactionResponse) GetFailedMutation() int32 {
+	if x != nil && x.FailedMutation != nil {
+		return *x.FailedMutation
+	}
+	return 0
+}
+
 // PosixLockRange is one advisory byte-range lock. Owner identity is (sid, owner):
 // sid is the mount session, owner the FUSE lock owner within it, so owners from
 // different mounts never alias. end is inclusive (max uint64 = to EOF); is_flock
@@ -7497,7 +7529,7 @@ const file_filer_proto_rawDesc = "" +
 	"\x18IF_EXTENDED_TIME_ELAPSED\x10\b\x12\x13\n" +
 	"\x0fIF_CHUNKS_EQUAL\x10\t\x12\x12\n" +
 	"\x0eIF_ENTRY_EQUAL\x10\n" +
-	"\"\xd0\x05\n" +
+	"\"\xad\x06\n" +
 	"\x0eObjectMutation\x121\n" +
 	"\x04type\x18\x01 \x01(\x0e2\x1d.filer_pb.ObjectMutation.TypeR\x04type\x12\x1c\n" +
 	"\tdirectory\x18\x02 \x01(\tR\tdirectory\x12\x12\n" +
@@ -7515,7 +7547,9 @@ const file_filer_proto_rawDesc = "" +
 	"\vtouch_mtime\x18\f \x01(\bR\n" +
 	"touchMtime\x12.\n" +
 	"\x13remove_empty_parent\x18\r \x01(\bR\x11removeEmptyParent\x12,\n" +
-	"\x12keep_remote_object\x18\x0e \x01(\bR\x10keepRemoteObject\x1a>\n" +
+	"\x12keep_remote_object\x18\x0e \x01(\bR\x10keepRemoteObject\x126\n" +
+	"\tcondition\x18\x0f \x01(\v2\x18.filer_pb.WriteConditionR\tcondition\x12#\n" +
+	"\rcondition_key\x18\x10 \x01(\tR\fconditionKey\x1a>\n" +
 	"\x10SetExtendedEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
 	"\x05value\x18\x02 \x01(\fR\x05value:\x028\x01\"E\n" +
@@ -7543,7 +7577,7 @@ const file_filer_proto_rawDesc = "" +
 	" \x01(\tR\x11onlyIfCurrentName\x1a?\n" +
 	"\x11CopyExtendedEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"\xa0\x03\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"\xd2\x03\n" +
 	"\x18ObjectTransactionRequest\x12\x19\n" +
 	"\block_key\x18\x01 \x01(\tR\alockKey\x126\n" +
 	"\tcondition\x18\x02 \x01(\v2\x18.filer_pb.WriteConditionR\tcondition\x126\n" +
@@ -7558,11 +7592,14 @@ const file_filer_proto_rawDesc = "" +
 	"\n" +
 	"request_id\x18\t \x01(\tR\trequestId\x12*\n" +
 	"\x11condition_alt_key\x18\n" +
-	" \x01(\tR\x0fconditionAltKey\"f\n" +
+	" \x01(\tR\x0fconditionAltKey\x120\n" +
+	"\x14condition_prefer_alt\x18\v \x01(\bR\x12conditionPreferAlt\"\xa8\x01\n" +
 	"\x19ObjectTransactionResponse\x12\x14\n" +
 	"\x05error\x18\x01 \x01(\tR\x05error\x123\n" +
 	"\n" +
-	"error_code\x18\x02 \x01(\x0e2\x14.filer_pb.FilerErrorR\terrorCode\"\xa1\x01\n" +
+	"error_code\x18\x02 \x01(\x0e2\x14.filer_pb.FilerErrorR\terrorCode\x12,\n" +
+	"\x0ffailed_mutation\x18\x03 \x01(\x05H\x00R\x0efailedMutation\x88\x01\x01B\x12\n" +
+	"\x10_failed_mutation\"\xa1\x01\n" +
 	"\x0ePosixLockRange\x12\x14\n" +
 	"\x05start\x18\x01 \x01(\x04R\x05start\x12\x10\n" +
 	"\x03end\x18\x02 \x01(\x04R\x03end\x12\x12\n" +
@@ -8220,136 +8257,137 @@ var file_filer_proto_depIdxs = []int32{
 	10,  // 17: filer_pb.ObjectMutation.entry:type_name -> filer_pb.Entry
 	101, // 18: filer_pb.ObjectMutation.set_extended:type_name -> filer_pb.ObjectMutation.SetExtendedEntry
 	20,  // 19: filer_pb.ObjectMutation.recompute:type_name -> filer_pb.Recompute
-	102, // 20: filer_pb.Recompute.copy_extended:type_name -> filer_pb.Recompute.CopyExtendedEntry
-	18,  // 21: filer_pb.ObjectTransactionRequest.condition:type_name -> filer_pb.WriteCondition
-	19,  // 22: filer_pb.ObjectTransactionRequest.mutations:type_name -> filer_pb.ObjectMutation
-	1,   // 23: filer_pb.ObjectTransactionResponse.error_code:type_name -> filer_pb.FilerError
-	2,   // 24: filer_pb.PosixLockRequest.op:type_name -> filer_pb.PosixLockOp
-	23,  // 25: filer_pb.PosixLockRequest.lock:type_name -> filer_pb.PosixLockRange
-	23,  // 26: filer_pb.PosixLockRequest.locks:type_name -> filer_pb.PosixLockRange
-	23,  // 27: filer_pb.PosixLockResponse.conflict:type_name -> filer_pb.PosixLockRange
-	21,  // 28: filer_pb.ObjectTransactionBatchRequest.transactions:type_name -> filer_pb.ObjectTransactionRequest
-	22,  // 29: filer_pb.ObjectTransactionBatchResponse.responses:type_name -> filer_pb.ObjectTransactionResponse
-	59,  // 30: filer_pb.CreateEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
-	1,   // 31: filer_pb.CreateEntryResponse.error_code:type_name -> filer_pb.FilerError
-	10,  // 32: filer_pb.UpdateEntryRequest.entry:type_name -> filer_pb.Entry
-	103, // 33: filer_pb.UpdateEntryRequest.expected_extended:type_name -> filer_pb.UpdateEntryRequest.ExpectedExtendedEntry
-	18,  // 34: filer_pb.UpdateEntryRequest.condition:type_name -> filer_pb.WriteCondition
-	59,  // 35: filer_pb.UpdateEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
-	13,  // 36: filer_pb.AppendToEntryRequest.chunks:type_name -> filer_pb.FileChunk
-	104, // 37: filer_pb.DeleteEntryRequest.expected_extended:type_name -> filer_pb.DeleteEntryRequest.ExpectedExtendedEntry
-	59,  // 38: filer_pb.DeleteEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
-	12,  // 39: filer_pb.StreamRenameEntryResponse.event_notification:type_name -> filer_pb.EventNotification
-	45,  // 40: filer_pb.AssignVolumeResponse.location:type_name -> filer_pb.Location
-	45,  // 41: filer_pb.AssignVolumeResponse.replicas:type_name -> filer_pb.Location
-	1,   // 42: filer_pb.AssignVolumeResponse.error_code:type_name -> filer_pb.FilerError
-	45,  // 43: filer_pb.Locations.locations:type_name -> filer_pb.Location
-	105, // 44: filer_pb.LookupVolumeResponse.locations_map:type_name -> filer_pb.LookupVolumeResponse.LocationsMapEntry
-	47,  // 45: filer_pb.CollectionListResponse.collections:type_name -> filer_pb.Collection
-	12,  // 46: filer_pb.SubscribeMetadataResponse.event_notification:type_name -> filer_pb.EventNotification
-	59,  // 47: filer_pb.SubscribeMetadataResponse.events:type_name -> filer_pb.SubscribeMetadataResponse
-	63,  // 48: filer_pb.SubscribeMetadataResponse.log_file_refs:type_name -> filer_pb.LogFileChunkRef
-	62,  // 49: filer_pb.ListMetadataSubscribersResponse.subscribers:type_name -> filer_pb.MetadataSubscriber
-	13,  // 50: filer_pb.LogFileChunkRef.chunks:type_name -> filer_pb.FileChunk
-	10,  // 51: filer_pb.TraverseBfsMetadataResponse.entry:type_name -> filer_pb.Entry
-	106, // 52: filer_pb.LocateBrokerResponse.resources:type_name -> filer_pb.LocateBrokerResponse.Resource
-	107, // 53: filer_pb.FilerConf.locations:type_name -> filer_pb.FilerConf.PathConf
-	10,  // 54: filer_pb.CacheRemoteObjectToLocalClusterResponse.entry:type_name -> filer_pb.Entry
-	59,  // 55: filer_pb.CacheRemoteObjectToLocalClusterResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
-	84,  // 56: filer_pb.TransferLocksRequest.locks:type_name -> filer_pb.Lock
-	17,  // 57: filer_pb.StreamMutateEntryRequest.create_request:type_name -> filer_pb.CreateEntryRequest
-	29,  // 58: filer_pb.StreamMutateEntryRequest.update_request:type_name -> filer_pb.UpdateEntryRequest
-	35,  // 59: filer_pb.StreamMutateEntryRequest.delete_request:type_name -> filer_pb.DeleteEntryRequest
-	39,  // 60: filer_pb.StreamMutateEntryRequest.rename_request:type_name -> filer_pb.StreamRenameEntryRequest
-	28,  // 61: filer_pb.StreamMutateEntryResponse.create_response:type_name -> filer_pb.CreateEntryResponse
-	30,  // 62: filer_pb.StreamMutateEntryResponse.update_response:type_name -> filer_pb.UpdateEntryResponse
-	36,  // 63: filer_pb.StreamMutateEntryResponse.delete_response:type_name -> filer_pb.DeleteEntryResponse
-	40,  // 64: filer_pb.StreamMutateEntryResponse.rename_response:type_name -> filer_pb.StreamRenameEntryResponse
-	95,  // 65: filer_pb.MountListResponse.mounts:type_name -> filer_pb.MountInfo
-	5,   // 66: filer_pb.LookupDirectoryEntriesRequest.requests:type_name -> filer_pb.LookupDirectoryEntryRequest
-	10,  // 67: filer_pb.LookupDirectoryEntryResult.entry:type_name -> filer_pb.Entry
-	97,  // 68: filer_pb.LookupDirectoryEntriesResponse.results:type_name -> filer_pb.LookupDirectoryEntryResult
-	108, // 69: filer_pb.LookupDirectoryEntriesResponse.locations_map:type_name -> filer_pb.LookupDirectoryEntriesResponse.LocationsMapEntry
-	109, // 70: filer_pb.LookupDirectoryEntriesResponse.read_auth:type_name -> filer_pb.LookupDirectoryEntriesResponse.ReadAuthEntry
-	3,   // 71: filer_pb.WriteCondition.Clause.kind:type_name -> filer_pb.WriteCondition.Kind
-	10,  // 72: filer_pb.WriteCondition.Clause.expected_entry:type_name -> filer_pb.Entry
-	44,  // 73: filer_pb.LookupVolumeResponse.LocationsMapEntry.value:type_name -> filer_pb.Locations
-	44,  // 74: filer_pb.LookupDirectoryEntriesResponse.LocationsMapEntry.value:type_name -> filer_pb.Locations
-	5,   // 75: filer_pb.SeaweedFiler.LookupDirectoryEntry:input_type -> filer_pb.LookupDirectoryEntryRequest
-	96,  // 76: filer_pb.SeaweedFiler.LookupDirectoryEntries:input_type -> filer_pb.LookupDirectoryEntriesRequest
-	7,   // 77: filer_pb.SeaweedFiler.ListEntries:input_type -> filer_pb.ListEntriesRequest
-	17,  // 78: filer_pb.SeaweedFiler.CreateEntry:input_type -> filer_pb.CreateEntryRequest
-	29,  // 79: filer_pb.SeaweedFiler.UpdateEntry:input_type -> filer_pb.UpdateEntryRequest
-	31,  // 80: filer_pb.SeaweedFiler.TouchAccessTime:input_type -> filer_pb.TouchAccessTimeRequest
-	33,  // 81: filer_pb.SeaweedFiler.AppendToEntry:input_type -> filer_pb.AppendToEntryRequest
-	35,  // 82: filer_pb.SeaweedFiler.DeleteEntry:input_type -> filer_pb.DeleteEntryRequest
-	21,  // 83: filer_pb.SeaweedFiler.ObjectTransaction:input_type -> filer_pb.ObjectTransactionRequest
-	26,  // 84: filer_pb.SeaweedFiler.ObjectTransactionBatch:input_type -> filer_pb.ObjectTransactionBatchRequest
-	24,  // 85: filer_pb.SeaweedFiler.PosixLock:input_type -> filer_pb.PosixLockRequest
-	37,  // 86: filer_pb.SeaweedFiler.AtomicRenameEntry:input_type -> filer_pb.AtomicRenameEntryRequest
-	39,  // 87: filer_pb.SeaweedFiler.StreamRenameEntry:input_type -> filer_pb.StreamRenameEntryRequest
-	89,  // 88: filer_pb.SeaweedFiler.StreamMutateEntry:input_type -> filer_pb.StreamMutateEntryRequest
-	41,  // 89: filer_pb.SeaweedFiler.AssignVolume:input_type -> filer_pb.AssignVolumeRequest
-	43,  // 90: filer_pb.SeaweedFiler.LookupVolume:input_type -> filer_pb.LookupVolumeRequest
-	48,  // 91: filer_pb.SeaweedFiler.CollectionList:input_type -> filer_pb.CollectionListRequest
-	50,  // 92: filer_pb.SeaweedFiler.DeleteCollection:input_type -> filer_pb.DeleteCollectionRequest
-	52,  // 93: filer_pb.SeaweedFiler.Statistics:input_type -> filer_pb.StatisticsRequest
-	54,  // 94: filer_pb.SeaweedFiler.Ping:input_type -> filer_pb.PingRequest
-	56,  // 95: filer_pb.SeaweedFiler.GetFilerConfiguration:input_type -> filer_pb.GetFilerConfigurationRequest
-	64,  // 96: filer_pb.SeaweedFiler.TraverseBfsMetadata:input_type -> filer_pb.TraverseBfsMetadataRequest
-	58,  // 97: filer_pb.SeaweedFiler.SubscribeMetadata:input_type -> filer_pb.SubscribeMetadataRequest
-	58,  // 98: filer_pb.SeaweedFiler.SubscribeLocalMetadata:input_type -> filer_pb.SubscribeMetadataRequest
-	60,  // 99: filer_pb.SeaweedFiler.ListMetadataSubscribers:input_type -> filer_pb.ListMetadataSubscribersRequest
-	71,  // 100: filer_pb.SeaweedFiler.KvGet:input_type -> filer_pb.KvGetRequest
-	73,  // 101: filer_pb.SeaweedFiler.KvPut:input_type -> filer_pb.KvPutRequest
-	76,  // 102: filer_pb.SeaweedFiler.CacheRemoteObjectToLocalCluster:input_type -> filer_pb.CacheRemoteObjectToLocalClusterRequest
-	78,  // 103: filer_pb.SeaweedFiler.DistributedLock:input_type -> filer_pb.LockRequest
-	80,  // 104: filer_pb.SeaweedFiler.DistributedUnlock:input_type -> filer_pb.UnlockRequest
-	82,  // 105: filer_pb.SeaweedFiler.FindLockOwner:input_type -> filer_pb.FindLockOwnerRequest
-	85,  // 106: filer_pb.SeaweedFiler.TransferLocks:input_type -> filer_pb.TransferLocksRequest
-	87,  // 107: filer_pb.SeaweedFiler.ReplicateLock:input_type -> filer_pb.ReplicateLockRequest
-	91,  // 108: filer_pb.SeaweedFiler.MountRegister:input_type -> filer_pb.MountRegisterRequest
-	93,  // 109: filer_pb.SeaweedFiler.MountList:input_type -> filer_pb.MountListRequest
-	6,   // 110: filer_pb.SeaweedFiler.LookupDirectoryEntry:output_type -> filer_pb.LookupDirectoryEntryResponse
-	98,  // 111: filer_pb.SeaweedFiler.LookupDirectoryEntries:output_type -> filer_pb.LookupDirectoryEntriesResponse
-	8,   // 112: filer_pb.SeaweedFiler.ListEntries:output_type -> filer_pb.ListEntriesResponse
-	28,  // 113: filer_pb.SeaweedFiler.CreateEntry:output_type -> filer_pb.CreateEntryResponse
-	30,  // 114: filer_pb.SeaweedFiler.UpdateEntry:output_type -> filer_pb.UpdateEntryResponse
-	32,  // 115: filer_pb.SeaweedFiler.TouchAccessTime:output_type -> filer_pb.TouchAccessTimeResponse
-	34,  // 116: filer_pb.SeaweedFiler.AppendToEntry:output_type -> filer_pb.AppendToEntryResponse
-	36,  // 117: filer_pb.SeaweedFiler.DeleteEntry:output_type -> filer_pb.DeleteEntryResponse
-	22,  // 118: filer_pb.SeaweedFiler.ObjectTransaction:output_type -> filer_pb.ObjectTransactionResponse
-	27,  // 119: filer_pb.SeaweedFiler.ObjectTransactionBatch:output_type -> filer_pb.ObjectTransactionBatchResponse
-	25,  // 120: filer_pb.SeaweedFiler.PosixLock:output_type -> filer_pb.PosixLockResponse
-	38,  // 121: filer_pb.SeaweedFiler.AtomicRenameEntry:output_type -> filer_pb.AtomicRenameEntryResponse
-	40,  // 122: filer_pb.SeaweedFiler.StreamRenameEntry:output_type -> filer_pb.StreamRenameEntryResponse
-	90,  // 123: filer_pb.SeaweedFiler.StreamMutateEntry:output_type -> filer_pb.StreamMutateEntryResponse
-	42,  // 124: filer_pb.SeaweedFiler.AssignVolume:output_type -> filer_pb.AssignVolumeResponse
-	46,  // 125: filer_pb.SeaweedFiler.LookupVolume:output_type -> filer_pb.LookupVolumeResponse
-	49,  // 126: filer_pb.SeaweedFiler.CollectionList:output_type -> filer_pb.CollectionListResponse
-	51,  // 127: filer_pb.SeaweedFiler.DeleteCollection:output_type -> filer_pb.DeleteCollectionResponse
-	53,  // 128: filer_pb.SeaweedFiler.Statistics:output_type -> filer_pb.StatisticsResponse
-	55,  // 129: filer_pb.SeaweedFiler.Ping:output_type -> filer_pb.PingResponse
-	57,  // 130: filer_pb.SeaweedFiler.GetFilerConfiguration:output_type -> filer_pb.GetFilerConfigurationResponse
-	65,  // 131: filer_pb.SeaweedFiler.TraverseBfsMetadata:output_type -> filer_pb.TraverseBfsMetadataResponse
-	59,  // 132: filer_pb.SeaweedFiler.SubscribeMetadata:output_type -> filer_pb.SubscribeMetadataResponse
-	59,  // 133: filer_pb.SeaweedFiler.SubscribeLocalMetadata:output_type -> filer_pb.SubscribeMetadataResponse
-	61,  // 134: filer_pb.SeaweedFiler.ListMetadataSubscribers:output_type -> filer_pb.ListMetadataSubscribersResponse
-	72,  // 135: filer_pb.SeaweedFiler.KvGet:output_type -> filer_pb.KvGetResponse
-	74,  // 136: filer_pb.SeaweedFiler.KvPut:output_type -> filer_pb.KvPutResponse
-	77,  // 137: filer_pb.SeaweedFiler.CacheRemoteObjectToLocalCluster:output_type -> filer_pb.CacheRemoteObjectToLocalClusterResponse
-	79,  // 138: filer_pb.SeaweedFiler.DistributedLock:output_type -> filer_pb.LockResponse
-	81,  // 139: filer_pb.SeaweedFiler.DistributedUnlock:output_type -> filer_pb.UnlockResponse
-	83,  // 140: filer_pb.SeaweedFiler.FindLockOwner:output_type -> filer_pb.FindLockOwnerResponse
-	86,  // 141: filer_pb.SeaweedFiler.TransferLocks:output_type -> filer_pb.TransferLocksResponse
-	88,  // 142: filer_pb.SeaweedFiler.ReplicateLock:output_type -> filer_pb.ReplicateLockResponse
-	92,  // 143: filer_pb.SeaweedFiler.MountRegister:output_type -> filer_pb.MountRegisterResponse
-	94,  // 144: filer_pb.SeaweedFiler.MountList:output_type -> filer_pb.MountListResponse
-	110, // [110:145] is the sub-list for method output_type
-	75,  // [75:110] is the sub-list for method input_type
-	75,  // [75:75] is the sub-list for extension type_name
-	75,  // [75:75] is the sub-list for extension extendee
-	0,   // [0:75] is the sub-list for field type_name
+	18,  // 20: filer_pb.ObjectMutation.condition:type_name -> filer_pb.WriteCondition
+	102, // 21: filer_pb.Recompute.copy_extended:type_name -> filer_pb.Recompute.CopyExtendedEntry
+	18,  // 22: filer_pb.ObjectTransactionRequest.condition:type_name -> filer_pb.WriteCondition
+	19,  // 23: filer_pb.ObjectTransactionRequest.mutations:type_name -> filer_pb.ObjectMutation
+	1,   // 24: filer_pb.ObjectTransactionResponse.error_code:type_name -> filer_pb.FilerError
+	2,   // 25: filer_pb.PosixLockRequest.op:type_name -> filer_pb.PosixLockOp
+	23,  // 26: filer_pb.PosixLockRequest.lock:type_name -> filer_pb.PosixLockRange
+	23,  // 27: filer_pb.PosixLockRequest.locks:type_name -> filer_pb.PosixLockRange
+	23,  // 28: filer_pb.PosixLockResponse.conflict:type_name -> filer_pb.PosixLockRange
+	21,  // 29: filer_pb.ObjectTransactionBatchRequest.transactions:type_name -> filer_pb.ObjectTransactionRequest
+	22,  // 30: filer_pb.ObjectTransactionBatchResponse.responses:type_name -> filer_pb.ObjectTransactionResponse
+	59,  // 31: filer_pb.CreateEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
+	1,   // 32: filer_pb.CreateEntryResponse.error_code:type_name -> filer_pb.FilerError
+	10,  // 33: filer_pb.UpdateEntryRequest.entry:type_name -> filer_pb.Entry
+	103, // 34: filer_pb.UpdateEntryRequest.expected_extended:type_name -> filer_pb.UpdateEntryRequest.ExpectedExtendedEntry
+	18,  // 35: filer_pb.UpdateEntryRequest.condition:type_name -> filer_pb.WriteCondition
+	59,  // 36: filer_pb.UpdateEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
+	13,  // 37: filer_pb.AppendToEntryRequest.chunks:type_name -> filer_pb.FileChunk
+	104, // 38: filer_pb.DeleteEntryRequest.expected_extended:type_name -> filer_pb.DeleteEntryRequest.ExpectedExtendedEntry
+	59,  // 39: filer_pb.DeleteEntryResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
+	12,  // 40: filer_pb.StreamRenameEntryResponse.event_notification:type_name -> filer_pb.EventNotification
+	45,  // 41: filer_pb.AssignVolumeResponse.location:type_name -> filer_pb.Location
+	45,  // 42: filer_pb.AssignVolumeResponse.replicas:type_name -> filer_pb.Location
+	1,   // 43: filer_pb.AssignVolumeResponse.error_code:type_name -> filer_pb.FilerError
+	45,  // 44: filer_pb.Locations.locations:type_name -> filer_pb.Location
+	105, // 45: filer_pb.LookupVolumeResponse.locations_map:type_name -> filer_pb.LookupVolumeResponse.LocationsMapEntry
+	47,  // 46: filer_pb.CollectionListResponse.collections:type_name -> filer_pb.Collection
+	12,  // 47: filer_pb.SubscribeMetadataResponse.event_notification:type_name -> filer_pb.EventNotification
+	59,  // 48: filer_pb.SubscribeMetadataResponse.events:type_name -> filer_pb.SubscribeMetadataResponse
+	63,  // 49: filer_pb.SubscribeMetadataResponse.log_file_refs:type_name -> filer_pb.LogFileChunkRef
+	62,  // 50: filer_pb.ListMetadataSubscribersResponse.subscribers:type_name -> filer_pb.MetadataSubscriber
+	13,  // 51: filer_pb.LogFileChunkRef.chunks:type_name -> filer_pb.FileChunk
+	10,  // 52: filer_pb.TraverseBfsMetadataResponse.entry:type_name -> filer_pb.Entry
+	106, // 53: filer_pb.LocateBrokerResponse.resources:type_name -> filer_pb.LocateBrokerResponse.Resource
+	107, // 54: filer_pb.FilerConf.locations:type_name -> filer_pb.FilerConf.PathConf
+	10,  // 55: filer_pb.CacheRemoteObjectToLocalClusterResponse.entry:type_name -> filer_pb.Entry
+	59,  // 56: filer_pb.CacheRemoteObjectToLocalClusterResponse.metadata_event:type_name -> filer_pb.SubscribeMetadataResponse
+	84,  // 57: filer_pb.TransferLocksRequest.locks:type_name -> filer_pb.Lock
+	17,  // 58: filer_pb.StreamMutateEntryRequest.create_request:type_name -> filer_pb.CreateEntryRequest
+	29,  // 59: filer_pb.StreamMutateEntryRequest.update_request:type_name -> filer_pb.UpdateEntryRequest
+	35,  // 60: filer_pb.StreamMutateEntryRequest.delete_request:type_name -> filer_pb.DeleteEntryRequest
+	39,  // 61: filer_pb.StreamMutateEntryRequest.rename_request:type_name -> filer_pb.StreamRenameEntryRequest
+	28,  // 62: filer_pb.StreamMutateEntryResponse.create_response:type_name -> filer_pb.CreateEntryResponse
+	30,  // 63: filer_pb.StreamMutateEntryResponse.update_response:type_name -> filer_pb.UpdateEntryResponse
+	36,  // 64: filer_pb.StreamMutateEntryResponse.delete_response:type_name -> filer_pb.DeleteEntryResponse
+	40,  // 65: filer_pb.StreamMutateEntryResponse.rename_response:type_name -> filer_pb.StreamRenameEntryResponse
+	95,  // 66: filer_pb.MountListResponse.mounts:type_name -> filer_pb.MountInfo
+	5,   // 67: filer_pb.LookupDirectoryEntriesRequest.requests:type_name -> filer_pb.LookupDirectoryEntryRequest
+	10,  // 68: filer_pb.LookupDirectoryEntryResult.entry:type_name -> filer_pb.Entry
+	97,  // 69: filer_pb.LookupDirectoryEntriesResponse.results:type_name -> filer_pb.LookupDirectoryEntryResult
+	108, // 70: filer_pb.LookupDirectoryEntriesResponse.locations_map:type_name -> filer_pb.LookupDirectoryEntriesResponse.LocationsMapEntry
+	109, // 71: filer_pb.LookupDirectoryEntriesResponse.read_auth:type_name -> filer_pb.LookupDirectoryEntriesResponse.ReadAuthEntry
+	3,   // 72: filer_pb.WriteCondition.Clause.kind:type_name -> filer_pb.WriteCondition.Kind
+	10,  // 73: filer_pb.WriteCondition.Clause.expected_entry:type_name -> filer_pb.Entry
+	44,  // 74: filer_pb.LookupVolumeResponse.LocationsMapEntry.value:type_name -> filer_pb.Locations
+	44,  // 75: filer_pb.LookupDirectoryEntriesResponse.LocationsMapEntry.value:type_name -> filer_pb.Locations
+	5,   // 76: filer_pb.SeaweedFiler.LookupDirectoryEntry:input_type -> filer_pb.LookupDirectoryEntryRequest
+	96,  // 77: filer_pb.SeaweedFiler.LookupDirectoryEntries:input_type -> filer_pb.LookupDirectoryEntriesRequest
+	7,   // 78: filer_pb.SeaweedFiler.ListEntries:input_type -> filer_pb.ListEntriesRequest
+	17,  // 79: filer_pb.SeaweedFiler.CreateEntry:input_type -> filer_pb.CreateEntryRequest
+	29,  // 80: filer_pb.SeaweedFiler.UpdateEntry:input_type -> filer_pb.UpdateEntryRequest
+	31,  // 81: filer_pb.SeaweedFiler.TouchAccessTime:input_type -> filer_pb.TouchAccessTimeRequest
+	33,  // 82: filer_pb.SeaweedFiler.AppendToEntry:input_type -> filer_pb.AppendToEntryRequest
+	35,  // 83: filer_pb.SeaweedFiler.DeleteEntry:input_type -> filer_pb.DeleteEntryRequest
+	21,  // 84: filer_pb.SeaweedFiler.ObjectTransaction:input_type -> filer_pb.ObjectTransactionRequest
+	26,  // 85: filer_pb.SeaweedFiler.ObjectTransactionBatch:input_type -> filer_pb.ObjectTransactionBatchRequest
+	24,  // 86: filer_pb.SeaweedFiler.PosixLock:input_type -> filer_pb.PosixLockRequest
+	37,  // 87: filer_pb.SeaweedFiler.AtomicRenameEntry:input_type -> filer_pb.AtomicRenameEntryRequest
+	39,  // 88: filer_pb.SeaweedFiler.StreamRenameEntry:input_type -> filer_pb.StreamRenameEntryRequest
+	89,  // 89: filer_pb.SeaweedFiler.StreamMutateEntry:input_type -> filer_pb.StreamMutateEntryRequest
+	41,  // 90: filer_pb.SeaweedFiler.AssignVolume:input_type -> filer_pb.AssignVolumeRequest
+	43,  // 91: filer_pb.SeaweedFiler.LookupVolume:input_type -> filer_pb.LookupVolumeRequest
+	48,  // 92: filer_pb.SeaweedFiler.CollectionList:input_type -> filer_pb.CollectionListRequest
+	50,  // 93: filer_pb.SeaweedFiler.DeleteCollection:input_type -> filer_pb.DeleteCollectionRequest
+	52,  // 94: filer_pb.SeaweedFiler.Statistics:input_type -> filer_pb.StatisticsRequest
+	54,  // 95: filer_pb.SeaweedFiler.Ping:input_type -> filer_pb.PingRequest
+	56,  // 96: filer_pb.SeaweedFiler.GetFilerConfiguration:input_type -> filer_pb.GetFilerConfigurationRequest
+	64,  // 97: filer_pb.SeaweedFiler.TraverseBfsMetadata:input_type -> filer_pb.TraverseBfsMetadataRequest
+	58,  // 98: filer_pb.SeaweedFiler.SubscribeMetadata:input_type -> filer_pb.SubscribeMetadataRequest
+	58,  // 99: filer_pb.SeaweedFiler.SubscribeLocalMetadata:input_type -> filer_pb.SubscribeMetadataRequest
+	60,  // 100: filer_pb.SeaweedFiler.ListMetadataSubscribers:input_type -> filer_pb.ListMetadataSubscribersRequest
+	71,  // 101: filer_pb.SeaweedFiler.KvGet:input_type -> filer_pb.KvGetRequest
+	73,  // 102: filer_pb.SeaweedFiler.KvPut:input_type -> filer_pb.KvPutRequest
+	76,  // 103: filer_pb.SeaweedFiler.CacheRemoteObjectToLocalCluster:input_type -> filer_pb.CacheRemoteObjectToLocalClusterRequest
+	78,  // 104: filer_pb.SeaweedFiler.DistributedLock:input_type -> filer_pb.LockRequest
+	80,  // 105: filer_pb.SeaweedFiler.DistributedUnlock:input_type -> filer_pb.UnlockRequest
+	82,  // 106: filer_pb.SeaweedFiler.FindLockOwner:input_type -> filer_pb.FindLockOwnerRequest
+	85,  // 107: filer_pb.SeaweedFiler.TransferLocks:input_type -> filer_pb.TransferLocksRequest
+	87,  // 108: filer_pb.SeaweedFiler.ReplicateLock:input_type -> filer_pb.ReplicateLockRequest
+	91,  // 109: filer_pb.SeaweedFiler.MountRegister:input_type -> filer_pb.MountRegisterRequest
+	93,  // 110: filer_pb.SeaweedFiler.MountList:input_type -> filer_pb.MountListRequest
+	6,   // 111: filer_pb.SeaweedFiler.LookupDirectoryEntry:output_type -> filer_pb.LookupDirectoryEntryResponse
+	98,  // 112: filer_pb.SeaweedFiler.LookupDirectoryEntries:output_type -> filer_pb.LookupDirectoryEntriesResponse
+	8,   // 113: filer_pb.SeaweedFiler.ListEntries:output_type -> filer_pb.ListEntriesResponse
+	28,  // 114: filer_pb.SeaweedFiler.CreateEntry:output_type -> filer_pb.CreateEntryResponse
+	30,  // 115: filer_pb.SeaweedFiler.UpdateEntry:output_type -> filer_pb.UpdateEntryResponse
+	32,  // 116: filer_pb.SeaweedFiler.TouchAccessTime:output_type -> filer_pb.TouchAccessTimeResponse
+	34,  // 117: filer_pb.SeaweedFiler.AppendToEntry:output_type -> filer_pb.AppendToEntryResponse
+	36,  // 118: filer_pb.SeaweedFiler.DeleteEntry:output_type -> filer_pb.DeleteEntryResponse
+	22,  // 119: filer_pb.SeaweedFiler.ObjectTransaction:output_type -> filer_pb.ObjectTransactionResponse
+	27,  // 120: filer_pb.SeaweedFiler.ObjectTransactionBatch:output_type -> filer_pb.ObjectTransactionBatchResponse
+	25,  // 121: filer_pb.SeaweedFiler.PosixLock:output_type -> filer_pb.PosixLockResponse
+	38,  // 122: filer_pb.SeaweedFiler.AtomicRenameEntry:output_type -> filer_pb.AtomicRenameEntryResponse
+	40,  // 123: filer_pb.SeaweedFiler.StreamRenameEntry:output_type -> filer_pb.StreamRenameEntryResponse
+	90,  // 124: filer_pb.SeaweedFiler.StreamMutateEntry:output_type -> filer_pb.StreamMutateEntryResponse
+	42,  // 125: filer_pb.SeaweedFiler.AssignVolume:output_type -> filer_pb.AssignVolumeResponse
+	46,  // 126: filer_pb.SeaweedFiler.LookupVolume:output_type -> filer_pb.LookupVolumeResponse
+	49,  // 127: filer_pb.SeaweedFiler.CollectionList:output_type -> filer_pb.CollectionListResponse
+	51,  // 128: filer_pb.SeaweedFiler.DeleteCollection:output_type -> filer_pb.DeleteCollectionResponse
+	53,  // 129: filer_pb.SeaweedFiler.Statistics:output_type -> filer_pb.StatisticsResponse
+	55,  // 130: filer_pb.SeaweedFiler.Ping:output_type -> filer_pb.PingResponse
+	57,  // 131: filer_pb.SeaweedFiler.GetFilerConfiguration:output_type -> filer_pb.GetFilerConfigurationResponse
+	65,  // 132: filer_pb.SeaweedFiler.TraverseBfsMetadata:output_type -> filer_pb.TraverseBfsMetadataResponse
+	59,  // 133: filer_pb.SeaweedFiler.SubscribeMetadata:output_type -> filer_pb.SubscribeMetadataResponse
+	59,  // 134: filer_pb.SeaweedFiler.SubscribeLocalMetadata:output_type -> filer_pb.SubscribeMetadataResponse
+	61,  // 135: filer_pb.SeaweedFiler.ListMetadataSubscribers:output_type -> filer_pb.ListMetadataSubscribersResponse
+	72,  // 136: filer_pb.SeaweedFiler.KvGet:output_type -> filer_pb.KvGetResponse
+	74,  // 137: filer_pb.SeaweedFiler.KvPut:output_type -> filer_pb.KvPutResponse
+	77,  // 138: filer_pb.SeaweedFiler.CacheRemoteObjectToLocalCluster:output_type -> filer_pb.CacheRemoteObjectToLocalClusterResponse
+	79,  // 139: filer_pb.SeaweedFiler.DistributedLock:output_type -> filer_pb.LockResponse
+	81,  // 140: filer_pb.SeaweedFiler.DistributedUnlock:output_type -> filer_pb.UnlockResponse
+	83,  // 141: filer_pb.SeaweedFiler.FindLockOwner:output_type -> filer_pb.FindLockOwnerResponse
+	86,  // 142: filer_pb.SeaweedFiler.TransferLocks:output_type -> filer_pb.TransferLocksResponse
+	88,  // 143: filer_pb.SeaweedFiler.ReplicateLock:output_type -> filer_pb.ReplicateLockResponse
+	92,  // 144: filer_pb.SeaweedFiler.MountRegister:output_type -> filer_pb.MountRegisterResponse
+	94,  // 145: filer_pb.SeaweedFiler.MountList:output_type -> filer_pb.MountListResponse
+	111, // [111:146] is the sub-list for method output_type
+	76,  // [76:111] is the sub-list for method input_type
+	76,  // [76:76] is the sub-list for extension type_name
+	76,  // [76:76] is the sub-list for extension extendee
+	0,   // [0:76] is the sub-list for field type_name
 }
 
 func init() { file_filer_proto_init() }
@@ -8358,6 +8396,7 @@ func file_filer_proto_init() {
 		return
 	}
 	file_filer_proto_msgTypes[4].OneofWrappers = []any{}
+	file_filer_proto_msgTypes[17].OneofWrappers = []any{}
 	file_filer_proto_msgTypes[84].OneofWrappers = []any{
 		(*StreamMutateEntryRequest_CreateRequest)(nil),
 		(*StreamMutateEntryRequest_UpdateRequest)(nil),
diff --git a/weed/pb/filer_pb/filer_vtproto.pb.go b/weed/pb/filer_pb/filer_vtproto.pb.go
index 8cd7734a72..9a3b40547c 100644
--- a/weed/pb/filer_pb/filer_vtproto.pb.go
+++ b/weed/pb/filer_pb/filer_vtproto.pb.go
@@ -1294,6 +1294,25 @@ func (m *ObjectMutation) MarshalToSizedBufferVT(dAtA []byte) (int, error) {
 		i -= len(m.unknownFields)
 		copy(dAtA[i:], m.unknownFields)
 	}
+	if len(m.ConditionKey) > 0 {
+		i -= len(m.ConditionKey)
+		copy(dAtA[i:], m.ConditionKey)
+		i = protohelpers.EncodeVarint(dAtA, i, uint64(len(m.ConditionKey)))
+		i--
+		dAtA[i] = 0x1
+		i--
+		dAtA[i] = 0x82
+	}
+	if m.Condition != nil {
+		size, err := m.Condition.MarshalToSizedBufferVT(dAtA[:i])
+		if err != nil {
+			return 0, err
+		}
+		i -= size
+		i = protohelpers.EncodeVarint(dAtA, i, uint64(size))
+		i--
+		dAtA[i] = 0x7a
+	}
 	if m.KeepRemoteObject {
 		i--
 		if m.KeepRemoteObject {
@@ -1579,6 +1598,16 @@ func (m *ObjectTransactionRequest) MarshalToSizedBufferVT(dAtA []byte) (int, err
 		i -= len(m.unknownFields)
 		copy(dAtA[i:], m.unknownFields)
 	}
+	if m.ConditionPreferAlt {
+		i--
+		if m.ConditionPreferAlt {
+			dAtA[i] = 1
+		} else {
+			dAtA[i] = 0
+		}
+		i--
+		dAtA[i] = 0x58
+	}
 	if len(m.ConditionAltKey) > 0 {
 		i -= len(m.ConditionAltKey)
 		copy(dAtA[i:], m.ConditionAltKey)
@@ -1710,6 +1739,11 @@ func (m *ObjectTransactionResponse) MarshalToSizedBufferVT(dAtA []byte) (int, er
 		i -= len(m.unknownFields)
 		copy(dAtA[i:], m.unknownFields)
 	}
+	if m.FailedMutation != nil {
+		i = protohelpers.EncodeVarint(dAtA, i, uint64(*m.FailedMutation))
+		i--
+		dAtA[i] = 0x18
+	}
 	if m.ErrorCode != 0 {
 		i = protohelpers.EncodeVarint(dAtA, i, uint64(m.ErrorCode))
 		i--
@@ -7191,6 +7225,14 @@ func (m *ObjectMutation) SizeVT() (n int) {
 	if m.KeepRemoteObject {
 		n += 2
 	}
+	if m.Condition != nil {
+		l = m.Condition.SizeVT()
+		n += 1 + l + protohelpers.SizeOfVarint(uint64(l))
+	}
+	l = len(m.ConditionKey)
+	if l > 0 {
+		n += 2 + l + protohelpers.SizeOfVarint(uint64(l))
+	}
 	n += len(m.unknownFields)
 	return n
 }
@@ -7297,6 +7339,9 @@ func (m *ObjectTransactionRequest) SizeVT() (n int) {
 	if l > 0 {
 		n += 1 + l + protohelpers.SizeOfVarint(uint64(l))
 	}
+	if m.ConditionPreferAlt {
+		n += 2
+	}
 	n += len(m.unknownFields)
 	return n
 }
@@ -7314,6 +7359,9 @@ func (m *ObjectTransactionResponse) SizeVT() (n int) {
 	if m.ErrorCode != 0 {
 		n += 1 + protohelpers.SizeOfVarint(uint64(m.ErrorCode))
 	}
+	if m.FailedMutation != nil {
+		n += 1 + protohelpers.SizeOfVarint(uint64(*m.FailedMutation))
+	}
 	n += len(m.unknownFields)
 	return n
 }
@@ -13244,6 +13292,74 @@ func (m *ObjectMutation) UnmarshalVT(dAtA []byte) error {
 				}
 			}
 			m.KeepRemoteObject = bool(v != 0)
+		case 15:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Condition", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return protohelpers.ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return protohelpers.ErrInvalidLength
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return protohelpers.ErrInvalidLength
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Condition == nil {
+				m.Condition = &WriteCondition{}
+			}
+			if err := m.Condition.UnmarshalVT(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 16:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field ConditionKey", wireType)
+			}
+			var stringLen uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return protohelpers.ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				stringLen |= uint64(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			intStringLen := int(stringLen)
+			if intStringLen < 0 {
+				return protohelpers.ErrInvalidLength
+			}
+			postIndex := iNdEx + intStringLen
+			if postIndex < 0 {
+				return protohelpers.ErrInvalidLength
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.ConditionKey = string(dAtA[iNdEx:postIndex])
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := protohelpers.Skip(dAtA[iNdEx:])
@@ -14097,6 +14213,26 @@ func (m *ObjectTransactionRequest) UnmarshalVT(dAtA []byte) error {
 			}
 			m.ConditionAltKey = string(dAtA[iNdEx:postIndex])
 			iNdEx = postIndex
+		case 11:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field ConditionPreferAlt", wireType)
+			}
+			var v int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return protohelpers.ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				v |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			m.ConditionPreferAlt = bool(v != 0)
 		default:
 			iNdEx = preIndex
 			skippy, err := protohelpers.Skip(dAtA[iNdEx:])
@@ -14199,6 +14335,26 @@ func (m *ObjectTransactionResponse) UnmarshalVT(dAtA []byte) error {
 					break
 				}
 			}
+		case 3:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field FailedMutation", wireType)
+			}
+			var v int32
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return protohelpers.ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				v |= int32(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			m.FailedMutation = &v
 		default:
 			iNdEx = preIndex
 			skippy, err := protohelpers.Skip(dAtA[iNdEx:])
diff --git a/weed/s3api/filer_multipart.go b/weed/s3api/filer_multipart.go
index 710b9db959..753246698a 100644
--- a/weed/s3api/filer_multipart.go
+++ b/weed/s3api/filer_multipart.go
@@ -689,6 +689,13 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 	// retries. With no owner yet (no ring), keep the lock as the bootstrap path.
 	owner := s3a.objectWriteOwner(*input.Bucket, *input.Key)
 	routeKey := s3a.objectRouteKey(*input.Bucket, *input.Key)
+	// The write condition rides the commit transaction so the owner filer
+	// evaluates it under the object's path lock — the gateway's earlier
+	// checkConditionalHeaders is only a fast-path. Conditions it cannot reduce
+	// (time-based, combined, ETag lists, weak ETags) keep the pre-change
+	// semantics: check and commit run under the distributed write lock, which
+	// routed writes still bypass.
+	cond, reducible := buildWriteCondition(r)
 	completionBody := func() s3err.ErrorCode {
 		var prepCode s3err.ErrorCode
 		completionState, output, prepCode = s3a.prepareMultipartCompletionState(r, input, parts, uploadDirectory, entryName, dirName, completedPartNumbers, completedPartMap, maxPartNo)
@@ -796,7 +803,7 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 					glog.Errorf("completeMultipartUpload %s upload %s unused part cleanup: %v", *input.Bucket, *input.UploadId, err)
 					return s3err.ErrInternalError
 				}
-				if code := s3a.routedMultipartFinalize(owner, *input.Bucket, *input.Key, useInvertedFormat, versionDir, versionFileName, completionState.finalParts, decorateVersionEntry, *input.UploadId); code != s3err.ErrNone {
+				if code := s3a.routedMultipartFinalize(owner, *input.Bucket, *input.Key, useInvertedFormat, versionDir, versionFileName, completionState.finalParts, decorateVersionEntry, *input.UploadId, cond); code != s3err.ErrNone {
 					if code == s3err.ErrNoSuchUpload {
 						return code
 					}
@@ -850,6 +857,9 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 				glog.Errorf("completeMultipartUpload %s upload %s unused part cleanup: %v", *input.Bucket, *input.UploadId, err)
 				return s3err.ErrInternalError
 			}
+			// The condition checks the null slot first, then the latest version,
+			// same resolution the gateway's conditional check performs.
+			versionsDir := dirName + "/" + entryName + s3_constants.VersionsFolder
 			if err := s3a.writeMultipartObject(owner, routeKey, dirName, entryName, completionState.finalParts, func(entry *filer_pb.Entry) {
 				if entry.Extended == nil {
 					entry.Extended = make(map[string][]byte)
@@ -898,10 +908,13 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 					entry.Attributes.Mime = completionState.mime
 				}
 				entry.Attributes.FileSize = uint64(completionState.offset)
-			}, removal); err != nil {
+			}, removal, cond, versionsDir); err != nil {
 				if errors.Is(err, errUploadRemoved) {
 					return s3err.ErrNoSuchUpload
 				}
+				if errors.Is(err, errObjectPrecondition) {
+					return s3err.ErrPreconditionFailed
+				}
 				// The transaction may have committed the object before failing on
 				// the upload removal; a surviving entry references the manifests.
 				if exists, err := s3a.exists(dirName, entryName, false); err != nil || exists {
@@ -991,10 +1004,13 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 			if completionState.entityWithTtl {
 				entry.Extended[s3_constants.SeaweedFSExpiresS3] = []byte("true")
 			}
-		}, removal); err != nil {
+		}, removal, cond, ""); err != nil {
 			if errors.Is(err, errUploadRemoved) {
 				return s3err.ErrNoSuchUpload
 			}
+			if errors.Is(err, errObjectPrecondition) {
+				return s3err.ErrPreconditionFailed
+			}
 			// The transaction may have committed the object before failing on
 			// the upload removal; a surviving entry references the manifests.
 			if exists, err := s3a.exists(dirName, entryName, false); err != nil || exists {
@@ -1017,7 +1033,7 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 		return s3err.ErrNone
 	}
 	var finalizeCode s3err.ErrorCode
-	if owner != "" {
+	if owner != "" && reducible {
 		if code := s3a.checkConditionalHeaders(r, *input.Bucket, *input.Key); code != s3err.ErrNone {
 			finalizeCode = code
 		} else {
diff --git a/weed/s3api/s3api_object_handlers_copy.go b/weed/s3api/s3api_object_handlers_copy.go
index 1b716126d9..2990eff785 100644
--- a/weed/s3api/s3api_object_handlers_copy.go
+++ b/weed/s3api/s3api_object_handlers_copy.go
@@ -742,7 +742,7 @@ func (s3a *S3ApiServer) finalizeCopyDestination(dstBucket, dstObject, dstVersion
 		if owner != "" {
 			err = s3a.routedMkFile(owner, s3a.objectRouteKey(dstBucket, normalizedObject), bucketDir+"/"+normalizedObject+s3_constants.VersionsFolder, versionFileName, dstEntry.Chunks, func(entry *filer_pb.Entry) {
 				copyEntryToTarget(entry, dstEntry)
-			}, nil)
+			}, nil, nil, "")
 		} else {
 			err = s3a.mkFile(bucketDir, versionObjectPath, dstEntry.Chunks, func(entry *filer_pb.Entry) {
 				copyEntryToTarget(entry, dstEntry)
@@ -779,7 +779,7 @@ func (s3a *S3ApiServer) finalizeCopyDestination(dstBucket, dstObject, dstVersion
 		owner := s3a.objectWriteOwner(dstBucket, normalizedObject)
 		if err = s3a.writeMultipartObject(owner, s3a.objectRouteKey(dstBucket, normalizedObject), dstDir, dstName, dstEntry.Chunks, func(entry *filer_pb.Entry) {
 			copyEntryToTarget(entry, dstEntry)
-		}, nil); err != nil {
+		}, nil, nil, ""); err != nil {
 			return "", "", err
 		}
 
@@ -799,7 +799,7 @@ func (s3a *S3ApiServer) finalizeCopyDestination(dstBucket, dstObject, dstVersion
 		// default filer is invisible to the next copy until replication.
 		if err = s3a.writeMultipartObject(s3a.objectWriteOwner(dstBucket, normalizedObject), s3a.objectRouteKey(dstBucket, normalizedObject), dstDir, dstName, dstEntry.Chunks, func(entry *filer_pb.Entry) {
 			copyEntryToTarget(entry, dstEntry)
-		}, nil); err != nil {
+		}, nil, nil, ""); err != nil {
 			return "", "", err
 		}
 
diff --git a/weed/s3api/s3api_object_handlers_put.go b/weed/s3api/s3api_object_handlers_put.go
index abe4e98607..502c73e7a5 100644
--- a/weed/s3api/s3api_object_handlers_put.go
+++ b/weed/s3api/s3api_object_handlers_put.go
@@ -1084,7 +1084,7 @@ func (s3a *S3ApiServer) putToFiler(r *http.Request, filePath string, dataReader
 				lockKey, finalizeMutations = finalize.lockKey, finalize.mutations
 			}
 			routeKey := s3a.objectRouteKey(bucket, object)
-			resp, err := s3a.routedPut(owner, routeKey, lockKey, filePath, entry, cond, "", condAltKey, finalizeMutations)
+			resp, err := s3a.routedPut(owner, routeKey, lockKey, filePath, entry, cond, "", condAltKey, false, nil, "", finalizeMutations)
 			if err == nil && resp.ErrorCode == filer_pb.FilerError_PRECONDITION_FAILED && condAltKey != "" {
 				// A filer that ignores condition_alt_key evaluated the empty
 				// null slot alone; resend the transaction against the entry the
@@ -1097,7 +1097,7 @@ func (s3a *S3ApiServer) putToFiler(r *http.Request, filePath string, dataReader
 					conditionKey = condAltKey + "/" + resolved.Name
 				}
 				glog.Warningf("putToFiler: routed PUT to %s precondition-failed for %s; resending against %s", owner, filePath, conditionKey)
-				resp, err = s3a.routedPut(owner, routeKey, lockKey, filePath, entry, cond, conditionKey, condAltKey, finalizeMutations)
+				resp, err = s3a.routedPut(owner, routeKey, lockKey, filePath, entry, cond, conditionKey, condAltKey, false, nil, "", finalizeMutations)
 			}
 			switch {
 			case err != nil:
diff --git a/weed/s3api/s3api_object_routed_write.go b/weed/s3api/s3api_object_routed_write.go
index be70ed1fcb..5c5b5bee7d 100644
--- a/weed/s3api/s3api_object_routed_write.go
+++ b/weed/s3api/s3api_object_routed_write.go
@@ -216,28 +216,37 @@ func (s3a *S3ApiServer) withWriteOwnerFilerClient(owner pb.ServerAddress, fn fun
 // object path plus a RECOMPUTE_LATEST finalize, so the version's PUT and its
 // .versions pointer flip commit atomically (the recompute scans .versions/ after
 // the PUT and sees the new version).
-func (s3a *S3ApiServer) routedPut(owner pb.ServerAddress, routeKey, lockKey, filePath string, entry *filer_pb.Entry, cond *filer_pb.WriteCondition, conditionKey, conditionAltKey string, finalize []*filer_pb.ObjectMutation) (*filer_pb.ObjectTransactionResponse, error) {
+// putCondition, when set, guards the PUT mutation itself against putConditionKey
+// (e.g. the upload directory a multipart commit must still find); the request
+// condition keeps guarding the object the transaction is about.
+func (s3a *S3ApiServer) routedPut(owner pb.ServerAddress, routeKey, lockKey, filePath string, entry *filer_pb.Entry, cond *filer_pb.WriteCondition, conditionKey, conditionAltKey string, conditionPreferAlt bool, putCondition *filer_pb.WriteCondition, putConditionKey string, finalize []*filer_pb.ObjectMutation) (*filer_pb.ObjectTransactionResponse, error) {
 	mutations := make([]*filer_pb.ObjectMutation, 0, 1+len(finalize))
 	mutations = append(mutations, &filer_pb.ObjectMutation{
-		Type:      filer_pb.ObjectMutation_PUT,
-		Directory: path.Dir(filePath),
-		Entry:     entry,
+		Type:         filer_pb.ObjectMutation_PUT,
+		Directory:    path.Dir(filePath),
+		Entry:        entry,
+		Condition:    putCondition,
+		ConditionKey: putConditionKey,
 	})
 	mutations = append(mutations, finalize...)
 	return s3a.objectTxnOnFiler(owner, &filer_pb.ObjectTransactionRequest{
-		LockKey:         lockKey,
-		RouteKey:        routeKey,
-		Condition:       cond,
-		ConditionKey:    conditionKey,
-		ConditionAltKey: conditionAltKey,
-		Mutations:       mutations,
+		LockKey:            lockKey,
+		RouteKey:           routeKey,
+		Condition:          cond,
+		ConditionKey:       conditionKey,
+		ConditionAltKey:    conditionAltKey,
+		ConditionPreferAlt: conditionPreferAlt,
+		Mutations:          mutations,
 	})
 }
 
 // routedMkFile builds an entry like filer_pb.MkFile and writes it through a
 // routed PUT on the owner filer, for callers that would otherwise mkFile to the
-// default filer (e.g. multipart completion of a non-versioned object).
-func (s3a *S3ApiServer) routedMkFile(owner pb.ServerAddress, routeKey, parentDir, name string, chunks []*filer_pb.FileChunk, fn func(*filer_pb.Entry), removal *uploadRemovalTxn) error {
+// default filer (e.g. multipart completion of a non-versioned object). cond is
+// the request's write condition, evaluated on the object under the transaction
+// lock; condAltKey falls back to the .versions directory when the object slot
+// is empty (suspended or versioned buckets).
+func (s3a *S3ApiServer) routedMkFile(owner pb.ServerAddress, routeKey, parentDir, name string, chunks []*filer_pb.FileChunk, fn func(*filer_pb.Entry), removal *uploadRemovalTxn, cond *filer_pb.WriteCondition, condAltKey string) error {
 	now := time.Now().Unix()
 	entry := &filer_pb.Entry{
 		Name: name,
@@ -254,14 +263,14 @@ func (s3a *S3ApiServer) routedMkFile(owner pb.ServerAddress, routeKey, parentDir
 		fn(entry)
 	}
 	filePath := parentDir + "/" + name
-	var cond *filer_pb.WriteCondition
-	var conditionKey string
+	var putCondition *filer_pb.WriteCondition
+	var putConditionKey string
 	var finalize []*filer_pb.ObjectMutation
 	if removal != nil {
-		cond, conditionKey = removal.condition, removal.conditionKey
+		putCondition, putConditionKey = removal.putCondition, removal.putConditionKey
 		finalize = []*filer_pb.ObjectMutation{removal.mutation}
 	}
-	resp, err := s3a.routedPut(owner, routeKey, filePath, filePath, entry, cond, conditionKey, "", finalize)
+	resp, err := s3a.routedPut(owner, routeKey, filePath, filePath, entry, cond, "", condAltKey, false, putCondition, putConditionKey, finalize)
 	if err != nil {
 		return err
 	}
@@ -269,12 +278,15 @@ func (s3a *S3ApiServer) routedMkFile(owner pb.ServerAddress, routeKey, parentDir
 		// Other keys are nested under this one, so the object goes onto the
 		// directory they live in — the same retry mkFile makes off the ring.
 		entry.MarkPrefixObject()
-		resp, err = s3a.routedPut(owner, routeKey, filePath, filePath, entry, cond, conditionKey, "", finalize)
+		resp, err = s3a.routedPut(owner, routeKey, filePath, filePath, entry, cond, "", condAltKey, false, putCondition, putConditionKey, finalize)
 		if err != nil {
 			return err
 		}
 	}
 	if resp.ErrorCode == filer_pb.FilerError_PRECONDITION_FAILED {
+		if resp.FailedMutation == nil {
+			return errObjectPrecondition
+		}
 		return errUploadRemoved
 	}
 	if resp.Error != "" {
@@ -283,32 +295,40 @@ func (s3a *S3ApiServer) routedMkFile(owner pb.ServerAddress, routeKey, parentDir
 	return nil
 }
 
-// errUploadRemoved is a routed commit rejected because its precondition found
-// the upload directory already deleted, mapped to NoSuchUpload by callers.
+// errUploadRemoved is a routed commit rejected because the upload directory's
+// precondition found it already deleted, mapped to NoSuchUpload by callers.
 var errUploadRemoved = errors.New("upload directory already removed")
 
+// errObjectPrecondition is a routed commit rejected because the request's write
+// condition (e.g. If-None-Match: *) found the object slot already taken by a
+// racing commit, mapped to PreconditionFailed by callers.
+var errObjectPrecondition = errors.New("object precondition failed")
+
 // writeMultipartObject writes a completed multipart object entry, routed to the
 // owner when known (so it serializes with concurrent writes to the same key)
 // and falling back to a plain mkFile otherwise. removal carries the upload
 // precondition and deletion applied in the same transaction as the routed PUT.
 // routeKey must be the same key the caller used to resolve owner, so owner
-// selection and forwarding stay consistent.
-func (s3a *S3ApiServer) writeMultipartObject(owner pb.ServerAddress, routeKey, dir, name string, chunks []*filer_pb.FileChunk, fn func(*filer_pb.Entry), removal *uploadRemovalTxn) error {
+// selection and forwarding stay consistent. cond is the request's write
+// condition, enforced on the owner under the transaction lock; condAltKey is
+// the .versions directory a conditional check falls back to when the bucket
+// tracks versions.
+func (s3a *S3ApiServer) writeMultipartObject(owner pb.ServerAddress, routeKey, dir, name string, chunks []*filer_pb.FileChunk, fn func(*filer_pb.Entry), removal *uploadRemovalTxn, cond *filer_pb.WriteCondition, condAltKey string) error {
 	if owner != "" {
-		return s3a.routedMkFile(owner, routeKey, dir, name, chunks, fn, removal)
+		return s3a.routedMkFile(owner, routeKey, dir, name, chunks, fn, removal, cond, condAltKey)
 	}
 	return s3a.mkFile(dir, name, chunks, fn)
 }
 
-// uploadRemovalTxn carries the precondition and mutation that drop a completed
-// upload's directory inside the object's commit transaction. The precondition
-// fails the commit when a delete that does not take the object lock (abort,
-// lifecycle, s3.clean.uploads) removed the directory first, instead of
-// publishing the object over freed chunks.
+// uploadRemovalTxn carries the PUT precondition and mutation that drop a
+// completed upload's directory inside the object's commit transaction. The
+// precondition fails the commit when a delete that does not take the object
+// lock (abort, lifecycle, s3.clean.uploads) removed the directory first,
+// instead of publishing the object over freed chunks.
 type uploadRemovalTxn struct {
-	condition    *filer_pb.WriteCondition
-	conditionKey string
-	mutation     *filer_pb.ObjectMutation
+	putCondition    *filer_pb.WriteCondition
+	putConditionKey string
+	mutation        *filer_pb.ObjectMutation
 }
 
 // routedUploadRemoval returns the transaction parts that remove a completed
@@ -319,14 +339,20 @@ func (s3a *S3ApiServer) routedUploadRemoval(ctx context.Context, owner pb.Server
 	if owner == "" {
 		return nil, nil
 	}
+	// Older filers ignore the mutation's upload-exists condition, so during an
+	// upgrade this gateway-side check keeps the same guard window the
+	// pre-transaction code had.
+	if exists, err := s3a.exists(s3a.genUploadsFolder(bucket), uploadId, true); err == nil && !exists {
+		return nil, errUploadRemoved
+	}
 	if err := s3a.deleteUnusedPartEntries(ctx, uploadDirectory, bucket, uploadId, completionState); err != nil {
 		return nil, err
 	}
 	conditionKey, condition := uploadExistsCondition(uploadDirectory)
 	return &uploadRemovalTxn{
-		condition:    condition,
-		conditionKey: conditionKey,
-		mutation:     s3a.removeUploadDirMutation(bucket, uploadId),
+		putCondition:    condition,
+		putConditionKey: conditionKey,
+		mutation:        s3a.removeUploadDirMutation(bucket, uploadId),
 	}, nil
 }
 
diff --git a/weed/s3api/s3api_object_routed_write_test.go b/weed/s3api/s3api_object_routed_write_test.go
index 0f23779d72..19f202c865 100644
--- a/weed/s3api/s3api_object_routed_write_test.go
+++ b/weed/s3api/s3api_object_routed_write_test.go
@@ -514,7 +514,7 @@ func TestRoutedMultipartFinalize(t *testing.T) {
 	chunks := []*filer_pb.FileChunk{{FileId: "1,01637037d6"}}
 	code := s3a.routedMultipartFinalize(owner, "b", "obj", false, "/buckets/b/obj.versions", "v_1", chunks, func(entry *filer_pb.Entry) {
 		entry.Extended = map[string][]byte{s3_constants.SeaweedFSUploadId: []byte("up1")}
-	}, "up1")
+	}, "up1", clause(filer_pb.WriteCondition_IF_NOT_EXISTS))
 	if code != s3err.ErrNone {
 		t.Fatalf("routedMultipartFinalize = %v", code)
 	}
@@ -529,10 +529,15 @@ func TestRoutedMultipartFinalize(t *testing.T) {
 	if req.RouteKey != "s3.object.write:/buckets/b/obj" {
 		t.Fatalf("RouteKey = %q", req.RouteKey)
 	}
-	if req.ConditionKey != "/buckets/b/.uploads/up1" {
+	// The request condition guards the object (at lock_key, falling back to
+	// .versions); the upload directory rides the PUT as a mutation guard.
+	if req.ConditionKey != "" {
 		t.Fatalf("ConditionKey = %q", req.ConditionKey)
 	}
-	if req.Condition == nil || len(req.Condition.Clauses) != 1 || req.Condition.Clauses[0].Kind != filer_pb.WriteCondition_IF_EXISTS {
+	if req.ConditionAltKey != "/buckets/b/obj.versions" {
+		t.Fatalf("ConditionAltKey = %q", req.ConditionAltKey)
+	}
+	if req.Condition == nil || len(req.Condition.Clauses) != 1 || req.Condition.Clauses[0].Kind != filer_pb.WriteCondition_IF_NOT_EXISTS {
 		t.Fatalf("Condition = %+v", req.Condition)
 	}
 	if len(req.Mutations) != 3 {
@@ -548,6 +553,10 @@ func TestRoutedMultipartFinalize(t *testing.T) {
 		string(put.Entry.Extended[s3_constants.SeaweedFSUploadId]) != "up1" {
 		t.Fatalf("put mutation = %+v", put)
 	}
+	if put.ConditionKey != "/buckets/b/.uploads/up1" ||
+		put.Condition == nil || len(put.Condition.Clauses) != 1 || put.Condition.Clauses[0].Kind != filer_pb.WriteCondition_IF_EXISTS {
+		t.Fatalf("put condition = %+v key %q", put.Condition, put.ConditionKey)
+	}
 	removeUpload := req.Mutations[1]
 	if removeUpload.Type != filer_pb.ObjectMutation_DELETE ||
 		removeUpload.Directory != "/buckets/b/.uploads" ||
@@ -580,7 +589,7 @@ func TestWriteMultipartObjectRemovesUploadDir(t *testing.T) {
 	if err != nil {
 		t.Fatalf("routedUploadRemoval: %v", err)
 	}
-	if err := s3a.writeMultipartObject(owner, "s3.object.write:/buckets/b/o", "/buckets/b", "o", nil, nil, removal); err != nil {
+	if err := s3a.writeMultipartObject(owner, "s3.object.write:/buckets/b/o", "/buckets/b", "o", nil, nil, removal, nil, ""); err != nil {
 		t.Fatalf("writeMultipartObject: %v", err)
 	}
 
@@ -591,12 +600,6 @@ func TestWriteMultipartObjectRemovesUploadDir(t *testing.T) {
 	if req.LockKey != "/buckets/b/o" {
 		t.Fatalf("LockKey = %q", req.LockKey)
 	}
-	if req.ConditionKey != "/buckets/b/.uploads/up1" {
-		t.Fatalf("ConditionKey = %q", req.ConditionKey)
-	}
-	if req.Condition == nil || len(req.Condition.Clauses) != 1 || req.Condition.Clauses[0].Kind != filer_pb.WriteCondition_IF_EXISTS {
-		t.Fatalf("Condition = %+v", req.Condition)
-	}
 	if len(req.Mutations) != 2 {
 		t.Fatalf("mutations = %d, want 2", len(req.Mutations))
 	}
@@ -604,6 +607,10 @@ func TestWriteMultipartObjectRemovesUploadDir(t *testing.T) {
 	if put.Type != filer_pb.ObjectMutation_PUT || put.Directory != "/buckets/b" || put.Entry == nil || put.Entry.Name != "o" {
 		t.Fatalf("put mutation = %+v", put)
 	}
+	if put.ConditionKey != "/buckets/b/.uploads/up1" ||
+		put.Condition == nil || len(put.Condition.Clauses) != 1 || put.Condition.Clauses[0].Kind != filer_pb.WriteCondition_IF_EXISTS {
+		t.Fatalf("put condition = %+v key %q", put.Condition, put.ConditionKey)
+	}
 	removeUpload := req.Mutations[1]
 	if removeUpload.Type != filer_pb.ObjectMutation_DELETE ||
 		removeUpload.Directory != "/buckets/b/.uploads" ||
diff --git a/weed/s3api/s3api_object_versioned_finalize.go b/weed/s3api/s3api_object_versioned_finalize.go
index 4f470a71de..c9ec86251a 100644
--- a/weed/s3api/s3api_object_versioned_finalize.go
+++ b/weed/s3api/s3api_object_versioned_finalize.go
@@ -116,8 +116,10 @@ func uploadExistsCondition(uploadDirectory string) (string, *filer_pb.WriteCondi
 // reachable: PUT first keeps the chunks referenced at all times, and removing
 // the upload directory before the recompute means a published object never
 // coexists with a leftover .uploads directory that s3.clean.uploads would purge
-// with data.
-func (s3a *S3ApiServer) routedMultipartFinalize(owner pb.ServerAddress, bucket, object string, useInvertedFormat bool, versionDir, versionFileName string, chunks []*filer_pb.FileChunk, decorate func(*filer_pb.Entry), uploadID string) s3err.ErrorCode {
+// with data. cond is the request's write condition, checked against the object
+// (its latest version when the slot at the object path is empty) under the same
+// lock; the upload directory rides the PUT as a mutation precondition.
+func (s3a *S3ApiServer) routedMultipartFinalize(owner pb.ServerAddress, bucket, object string, useInvertedFormat bool, versionDir, versionFileName string, chunks []*filer_pb.FileChunk, decorate func(*filer_pb.Entry), uploadID string, cond *filer_pb.WriteCondition) s3err.ErrorCode {
 	now := time.Now().Unix()
 	versionEntry := &filer_pb.Entry{
 		Name: versionFileName,
@@ -138,8 +140,14 @@ func (s3a *S3ApiServer) routedMultipartFinalize(owner pb.ServerAddress, bucket,
 	if owner != "" {
 		routeKey = s3a.objectRouteKey(bucket, object)
 	}
-	conditionKey, condition := uploadExistsCondition(s3a.genUploadsFolder(bucket) + "/" + uploadID)
-	resp, err := s3a.routedPut(owner, routeKey, s3a.toFilerPath(bucket, object), versionDir+"/"+versionFileName, versionEntry, condition, conditionKey, "", []*filer_pb.ObjectMutation{
+	// A filer older than the mutation-condition support silently ignores
+	// putCondition, so on upgrade the guard degrades to this gateway-side
+	// check — the same window the pre-transaction code had.
+	if exists, err := s3a.exists(s3a.genUploadsFolder(bucket), uploadID, true); err == nil && !exists {
+		return s3err.ErrNoSuchUpload
+	}
+	putConditionKey, putCondition := uploadExistsCondition(s3a.genUploadsFolder(bucket) + "/" + uploadID)
+	resp, err := s3a.routedPut(owner, routeKey, s3a.toFilerPath(bucket, object), versionDir+"/"+versionFileName, versionEntry, cond, "", versionDir, true, putCondition, putConditionKey, []*filer_pb.ObjectMutation{
 		s3a.removeUploadDirMutation(bucket, uploadID),
 		s3a.latestPointerRecompute(bucket, object, useInvertedFormat, "", true),
 	})
@@ -148,6 +156,9 @@ func (s3a *S3ApiServer) routedMultipartFinalize(owner pb.ServerAddress, bucket,
 		glog.Errorf("routedMultipartFinalize: %s/%s upload %s on %s: %v", bucket, object, uploadID, owner, err)
 		return s3err.ErrInternalError
 	case resp.ErrorCode == filer_pb.FilerError_PRECONDITION_FAILED:
+		if resp.FailedMutation == nil {
+			return s3err.ErrPreconditionFailed
+		}
 		return s3err.ErrNoSuchUpload
 	case resp.Error != "":
 		glog.Errorf("routedMultipartFinalize: %s/%s upload %s: %s", bucket, object, uploadID, resp.Error)
diff --git a/weed/server/filer_grpc_server.go b/weed/server/filer_grpc_server.go
index 21f823410b..498bdd624c 100644
--- a/weed/server/filer_grpc_server.go
+++ b/weed/server/filer_grpc_server.go
@@ -353,6 +353,7 @@ func (fs *FilerServer) ObjectTransaction(ctx context.Context, req *filer_pb.Obje
 			IsMoved:            true,
 			RequestId:          req.RequestId,
 			ConditionAltKey:    req.ConditionAltKey,
+			ConditionPreferAlt: req.ConditionPreferAlt,
 		}
 		var resp *filer_pb.ObjectTransactionResponse
 		handled, err := fs.forwardToWriteOwner(ctx, req.RouteKey, func(owner pb.ServerAddress) error {
@@ -407,11 +408,16 @@ func (fs *FilerServer) ObjectTransaction(ctx context.Context, req *filer_pb.Obje
 		}
 		current, findErr := fs.filer.FindEntry(ctx, conditionPath)
 		if findErr == nil && current != nil && current.IsDirectory() && req.ConditionAltKey != "" {
-			// A directory is not the object: implicit directories can share a
-			// path with an S3 key, so treat it as an absent slot. Only the
-			// alt-key callers want object-slot semantics; an explicit
-			// condition_key may legitimately name a directory.
-			current, findErr = nil, filer_pb.ErrNotFound
+			// A bare directory is not the object: implicit directories can
+			// share a path with an S3 key, so treat it as an absent slot. A
+			// directory entry holding content or the prefix-object marker is
+			// an object and stays. Only the alt-key callers want object-slot
+			// semantics; an explicit condition_key may legitimately name a
+			// directory.
+			_, isPrefixObject := current.Extended[s3_constants.SeaweedFSPrefixObject]
+			if current.Mime == "" && len(current.GetChunks()) == 0 && len(current.Content) == 0 && !current.IsInRemoteOnly() && !isPrefixObject {
+				current, findErr = nil, filer_pb.ErrNotFound
+			}
 		}
 		// The caller can name a fallback evaluated when the primary is absent —
 		// a suspended-versioning write checks "the null slot if present, else
@@ -419,8 +425,24 @@ func (fs *FilerServer) ObjectTransaction(ctx context.Context, req *filer_pb.Obje
 		// the object's .versions directory, and the latest it resolves to is
 		// read from the pointer maintained by the same lock, so a concurrent
 		// version delete cannot move which entry the condition sees.
-		if findErr == filer_pb.ErrNotFound && req.ConditionAltKey != "" {
-			current, conditionPath, findErr = fs.latestVersionedConditionEntry(ctx, util.FullPath(req.ConditionAltKey))
+		if req.ConditionAltKey != "" {
+			altEntry, altPath, altErr := fs.latestVersionedConditionEntry(ctx, util.FullPath(req.ConditionAltKey))
+			if req.ConditionPreferAlt {
+				// The versioned path resolves "current" through the latest
+				// pointer, so a stale null-version entry or a tombstoned
+				// latest decides correctly. When the alt path cannot resolve
+				// (no .versions at all), the primary entry stands.
+				switch {
+				case altErr == nil:
+					current, conditionPath, findErr = altEntry, altPath, nil
+				case errors.Is(altErr, filer_pb.ErrNotFound):
+				default:
+					record = false
+					return nil, fmt.Errorf("ObjectTransaction condition %s: %w", conditionPath, altErr)
+				}
+			} else if findErr == filer_pb.ErrNotFound {
+				current, conditionPath, findErr = altEntry, altPath, altErr
+			}
 		}
 		if findErr != nil && findErr != filer_pb.ErrNotFound {
 			record = false // a lookup error decides nothing; a retry must re-run, not replay
@@ -438,10 +460,26 @@ func (fs *FilerServer) ObjectTransaction(ctx context.Context, req *filer_pb.Obje
 	}
 
 	for i, m := range req.Mutations {
+		if code, err := fs.checkMutationCondition(ctx, m); err != nil {
+			glog.V(2).InfofCtx(ctx, "ObjectTransaction %s mutation %d condition lookup: %v", lockPath, i, err)
+			resp.Error = fmt.Sprintf("mutation %d: %v", i, err)
+			failed := int32(i)
+			resp.FailedMutation = &failed
+			return resp, nil
+		} else if code != filer_pb.FilerError_OK {
+			glog.V(3).InfofCtx(ctx, "ObjectTransaction %s mutation %d precondition failed", lockPath, i)
+			resp.Error = fmt.Sprintf("mutation %d: precondition failed", i)
+			resp.ErrorCode = code
+			failed := int32(i)
+			resp.FailedMutation = &failed
+			return resp, nil
+		}
 		if err := fs.applyObjectMutation(ctx, m, req.IsFromOtherCluster, req.Signatures); err != nil {
 			glog.V(2).InfofCtx(ctx, "ObjectTransaction %s mutation %d (%v): %v", lockPath, i, m.Type, err)
 			resp.Error = fmt.Sprintf("mutation %d: %v", i, err)
 			resp.ErrorCode = filerErrorCode(err)
+			failed := int32(i)
+			resp.FailedMutation = &failed
 			return resp, nil
 		}
 	}
@@ -449,6 +487,36 @@ func (fs *FilerServer) ObjectTransaction(ctx context.Context, req *filer_pb.Obje
 	return resp, nil
 }
 
+// checkMutationCondition evaluates a mutation's optional precondition under the
+// transaction's lock, against condition_key when set or the mutation's target
+// (the PUT's entry path, else directory/name). Unlike the request-level
+// condition there is no alt-key fallback: a mutation guard names the exact entry
+// it guards.
+func (fs *FilerServer) checkMutationCondition(ctx context.Context, m *filer_pb.ObjectMutation) (filer_pb.FilerError, error) {
+	if !conditionIsSet(m.Condition) {
+		return filer_pb.FilerError_OK, nil
+	}
+	target := util.FullPath(m.ConditionKey)
+	if target == "" {
+		name := m.Name
+		if m.Type == filer_pb.ObjectMutation_PUT && m.Entry != nil {
+			name = m.Entry.Name
+		}
+		target = util.JoinPath(m.Directory, name)
+	}
+	current, err := fs.filer.FindEntry(ctx, target)
+	if err != nil && err != filer_pb.ErrNotFound {
+		return filer_pb.FilerError_OK, fmt.Errorf("condition check %s: %w", target, err)
+	}
+	if err == filer_pb.ErrNotFound {
+		current = nil
+	}
+	if !writeConditionSatisfied(m.Condition, current) {
+		return filer_pb.FilerError_PRECONDITION_FAILED, nil
+	}
+	return filer_pb.FilerError_OK, nil
+}
+
 const (
 	recentObjectTxnTTL         = 2 * time.Minute
 	recentObjectTxnSweepCap    = 10000
@@ -525,9 +593,11 @@ func (fs *FilerServer) rememberObjectTxn(requestID string, lockPath util.FullPat
 // latestVersionedConditionEntry resolves the object a conditional write should
 // be checked against inside a .versions directory: the entry the latest-version
 // pointer names, or nothing when the pointer names a delete marker — a
-// tombstone is not a current version. A missing pointer or a pointer to a file
-// that is gone means the metadata cannot answer the question, which reports an
-// error rather than guessing at either branch.
+// tombstone is not a current version. A suspended-versioning write clears the
+// pointer and stamps null-version-is-latest instead, which reports not-found so
+// the regular path's null object decides. Any other missing pointer, or a
+// pointer to a file that is gone, means the metadata cannot answer the
+// question, which reports an error rather than guessing at either branch.
 func (fs *FilerServer) latestVersionedConditionEntry(ctx context.Context, versionsDir util.FullPath) (*filer.Entry, util.FullPath, error) {
 	versionsEntry, err := fs.filer.FindEntry(ctx, versionsDir)
 	if err != nil {
@@ -538,6 +608,9 @@ func (fs *FilerServer) latestVersionedConditionEntry(ctx context.Context, versio
 	}
 	latestName := string(versionsEntry.Extended[s3_constants.ExtLatestVersionFileNameKey])
 	if latestName == "" {
+		if string(versionsEntry.Extended[s3_constants.ExtNullVersionIsLatestKey]) == "true" {
+			return nil, versionsDir, filer_pb.ErrNotFound
+		}
 		return nil, versionsDir, fmt.Errorf("%s has no latest-version pointer", versionsDir)
 	}
 	latestPath := util.NewFullPath(string(versionsDir), latestName)
@@ -549,7 +622,7 @@ func (fs *FilerServer) latestVersionedConditionEntry(ctx context.Context, versio
 		return nil, latestPath, err
 	}
 	if string(entry.Extended[s3_constants.ExtDeleteMarkerKey]) == "true" {
-		return nil, latestPath, filer_pb.ErrNotFound
+		return nil, latestPath, nil
 	}
 	return entry, latestPath, nil
 }
diff --git a/weed/server/filer_grpc_server_object_txn_test.go b/weed/server/filer_grpc_server_object_txn_test.go
index c73badd7a3..b7fd0b5117 100644
--- a/weed/server/filer_grpc_server_object_txn_test.go
+++ b/weed/server/filer_grpc_server_object_txn_test.go
@@ -229,6 +229,90 @@ func TestObjectTransactionPreconditionAborts(t *testing.T) {
 	}
 }
 
+// A mutation's own precondition is checked under the same lock just before the
+// mutation applies; a failure aborts the transaction at that mutation and is
+// reported through failed_mutation, leaving earlier mutations' work visible.
+func TestObjectTransactionMutationCondition(t *testing.T) {
+	now := time.Unix(1700000000, 0)
+	fs, store := newTxnTestServer(t, map[string]*filer.Entry{
+		"/buckets/bkt/obj": {
+			Attr: filer.Attr{Inode: 1, Mtime: now, Crtime: now, Mode: 0644},
+		},
+	})
+
+	mkReq := func() *filer_pb.ObjectTransactionRequest {
+		return &filer_pb.ObjectTransactionRequest{
+			LockKey: "/buckets/bkt/obj",
+			Mutations: []*filer_pb.ObjectMutation{
+				{Type: filer_pb.ObjectMutation_PUT, Directory: "/buckets/bkt", Entry: &filer_pb.Entry{
+					Name:       "other",
+					Attributes: &filer_pb.FuseAttributes{Mtime: now.Unix(), FileMode: 0644, Inode: 2},
+				}, Condition: &filer_pb.WriteCondition{Clauses: []*filer_pb.WriteCondition_Clause{
+					{Kind: filer_pb.WriteCondition_IF_NOT_EXISTS},
+				}}, ConditionKey: "/buckets/bkt/obj"},
+				{Type: filer_pb.ObjectMutation_DELETE, Directory: "/buckets/bkt", Name: "obj"},
+			},
+		}
+	}
+
+	resp, err := fs.ObjectTransaction(context.Background(), mkReq())
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if resp.ErrorCode != filer_pb.FilerError_PRECONDITION_FAILED {
+		t.Fatalf("want PRECONDITION_FAILED, got %v (%q)", resp.ErrorCode, resp.Error)
+	}
+	if resp.FailedMutation == nil || *resp.FailedMutation != 0 {
+		t.Fatalf("want failed_mutation=0, got %v", resp.FailedMutation)
+	}
+	if _, ok := store.entries["/buckets/bkt/other"]; ok {
+		t.Errorf("PUT whose condition failed must not store an entry")
+	}
+	if _, ok := store.entries["/buckets/bkt/obj"]; !ok {
+		t.Errorf("a failed mutation condition must abort before later mutations run")
+	}
+
+	// With the slot absent the same transaction applies both mutations.
+	delete(store.entries, "/buckets/bkt/obj")
+	resp, err = fs.ObjectTransaction(context.Background(), mkReq())
+	if err != nil || resp.Error != "" {
+		t.Fatalf("txn failed: err=%v resp=%q", err, resp.Error)
+	}
+	if _, ok := store.entries["/buckets/bkt/other"]; !ok {
+		t.Errorf("condition satisfied: PUT entry missing")
+	}
+}
+
+// The request-level condition keeps reporting no failed_mutation, so callers
+// can tell it apart from a mutation's own guard.
+func TestObjectTransactionMutationConditionVsRequest(t *testing.T) {
+	now := time.Unix(1700000000, 0)
+	fs, _ := newTxnTestServer(t, map[string]*filer.Entry{
+		"/buckets/bkt/obj": {
+			Attr: filer.Attr{Inode: 1, Mtime: now, Crtime: now, Mode: 0644},
+		},
+	})
+
+	resp, err := fs.ObjectTransaction(context.Background(), &filer_pb.ObjectTransactionRequest{
+		LockKey: "/buckets/bkt/obj",
+		Condition: &filer_pb.WriteCondition{Clauses: []*filer_pb.WriteCondition_Clause{
+			{Kind: filer_pb.WriteCondition_IF_NOT_EXISTS},
+		}},
+		Mutations: []*filer_pb.ObjectMutation{
+			{Type: filer_pb.ObjectMutation_DELETE, Directory: "/buckets/bkt", Name: "obj"},
+		},
+	})
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if resp.ErrorCode != filer_pb.FilerError_PRECONDITION_FAILED {
+		t.Fatalf("want PRECONDITION_FAILED, got %v (%q)", resp.ErrorCode, resp.Error)
+	}
+	if resp.FailedMutation != nil {
+		t.Fatalf("request-level failure must not set failed_mutation, got %d", *resp.FailedMutation)
+	}
+}
+
 // Deleting the latest version and recomputing re-points the pointer at the new
 // highest-named remaining version; the scan runs under the transaction lock.
 func TestObjectTransactionRecomputeLatest(t *testing.T) {
@@ -1095,3 +1179,42 @@ func TestObjectTransactionConditionIgnoresDirectory(t *testing.T) {
 		t.Fatalf("directory at key with live latest: err=%v code=%v, want precondition failed", err, resp.GetErrorCode())
 	}
 }
+
+// A suspended-versioning write clears the latest-version pointer and leaves
+// the null object at the regular path as current. The prefer-alt condition
+// must keep resolving against that object, not reject on the empty pointer.
+func TestObjectTransactionConditionPreferAltHonorsNullIsLatest(t *testing.T) {
+	now := time.Unix(1700000000, 0)
+	seed := map[string]*filer.Entry{
+		"/buckets/bkt/obj": {
+			Attr:     filer.Attr{Inode: 1, Mtime: now, Crtime: now, Mode: 0644},
+			Extended: map[string][]byte{s3_constants.ExtETagKey: []byte("nulletag")},
+		},
+		"/buckets/bkt/obj/.versions": {
+			Attr:     filer.Attr{Inode: 2, Mtime: now, Crtime: now, Mode: 0755},
+			Extended: map[string][]byte{s3_constants.ExtNullVersionIsLatestKey: []byte("true")},
+		},
+	}
+	req := &filer_pb.ObjectTransactionRequest{
+		LockKey:            "/buckets/bkt/obj",
+		ConditionAltKey:    "/buckets/bkt/obj/.versions",
+		ConditionPreferAlt: true,
+		Condition: &filer_pb.WriteCondition{
+			Clauses: []*filer_pb.WriteCondition_Clause{{Kind: filer_pb.WriteCondition_IF_ETAG_MATCH, Etags: []string{`"nulletag"`}}},
+		},
+		Mutations: []*filer_pb.ObjectMutation{{
+			Type:      filer_pb.ObjectMutation_PUT,
+			Directory: "/buckets/bkt",
+			Entry:     &filer_pb.Entry{Name: "obj", Attributes: &filer_pb.FuseAttributes{Mtime: now.Unix(), FileMode: 0644, Inode: 9}},
+		}},
+	}
+
+	fs, store := newTxnTestServer(t, seed)
+	resp, err := fs.ObjectTransaction(context.Background(), req)
+	if err != nil || resp.Error != "" {
+		t.Fatalf("null-is-latest: err=%v resp=%q, want applied", err, resp.Error)
+	}
+	if store.entries["/buckets/bkt/obj"] == nil {
+		t.Fatal("mutation did not apply over a null-is-latest .versions")
+	}
+}