diff --git a/weed/s3api/filer_multipart.go b/weed/s3api/filer_multipart.go
index 6be70b8adf..9a66b6f879 100644
--- a/weed/s3api/filer_multipart.go
+++ b/weed/s3api/filer_multipart.go
@@ -1156,15 +1156,17 @@ func (s3a *S3ApiServer) abortMultipartUpload(input *s3.AbortMultipartUploadInput
 
 	uploadsFolder := s3a.genUploadsFolder(*input.Bucket)
 	uploadEntry, err := s3a.getEntry(uploadsFolder, *input.UploadId)
+	// complete and abort both remove .uploads/<id>; a missing record is an upload
+	// that does not exist (NoSuchUpload on AWS), not one this call discarded
 	if err != nil {
 		if isFilerNotFound(err) {
-			return &s3.AbortMultipartUploadOutput{}, s3err.ErrNone
+			return nil, s3err.ErrNoSuchUpload
 		}
 		glog.Errorf("bucket %s abort upload %s: %v", *input.Bucket, *input.UploadId, err)
 		return nil, s3err.ErrInternalError
 	}
 	if uploadEntry == nil {
-		return &s3.AbortMultipartUploadOutput{}, s3err.ErrNone
+		return nil, s3err.ErrNoSuchUpload
 	}
 
 	object := string(uploadEntry.Extended[s3_constants.ExtMultipartObjectKey])
diff --git a/weed/s3api/filer_multipart_abort_test.go b/weed/s3api/filer_multipart_abort_test.go
index 37f3945afd..fc1af1d300 100644
--- a/weed/s3api/filer_multipart_abort_test.go
+++ b/weed/s3api/filer_multipart_abort_test.go
@@ -189,14 +189,36 @@ func TestAbortUndecidableCheckRefuses(t *testing.T) {
 	}
 }
 
-// No upload directory at all answers success, the same as before.
-func TestAbortGoneUploadAnswersSuccess(t *testing.T) {
-	s3a := newAbortTestServer(t, &fakeAbortFiler{})
+// No upload directory at all is an upload that does not exist: NoSuchUpload
+// (404), as on AWS, not a successful abort.
+func TestAbortGoneUploadAnswersNoSuchUpload(t *testing.T) {
+	f := &fakeAbortFiler{}
+	s3a := newAbortTestServer(t, f)
 
 	_, code := s3a.abortMultipartUpload(abortInput("gone"))
 
-	if code != s3err.ErrNone {
-		t.Fatalf("code = %v, want ErrNone", code)
+	if code != s3err.ErrNoSuchUpload {
+		t.Fatalf("code = %v, want ErrNoSuchUpload", code)
+	}
+	if f.deleteReq != nil {
+		t.Fatalf("delete issued for a missing upload: %+v", f.deleteReq)
+	}
+}
+
+// Completion removes .uploads/<id>; aborting the completed upload afterwards
+// must say NoSuchUpload, not 204, so the client cannot read it as the object
+// being discarded, and must not touch the object.
+func TestAbortAfterCompleteAnswersNoSuchUpload(t *testing.T) {
+	f := &fakeAbortFiler{objectEntry: versionEntry("a.bin", "up1")}
+	s3a := newAbortTestServer(t, f)
+
+	_, code := s3a.abortMultipartUpload(abortInput("up1"))
+
+	if code != s3err.ErrNoSuchUpload {
+		t.Fatalf("code = %v, want ErrNoSuchUpload", code)
+	}
+	if f.deleteReq != nil {
+		t.Fatalf("delete issued after completion: %+v", f.deleteReq)
 	}
 }
 
diff --git a/weed/s3api/s3api_object_handlers_multipart.go b/weed/s3api/s3api_object_handlers_multipart.go
index c28778a594..c817027f60 100644
--- a/weed/s3api/s3api_object_handlers_multipart.go
+++ b/weed/s3api/s3api_object_handlers_multipart.go
@@ -546,7 +546,7 @@ func (s3a *S3ApiServer) checkUploadStillOpen(w http.ResponseWriter, r *http.Requ
 		Bucket:   aws.String(bucket),
 		Key:      objectKey(aws.String(object)),
 		UploadId: aws.String(uploadID),
-	}); code != s3err.ErrNone {
+	}); code != s3err.ErrNone && code != s3err.ErrNoSuchUpload {
 		glog.Warningf("checkUploadStillOpen %s/%s: part left behind, cleanup failed", bucket, uploadID)
 	}
 	s3err.WriteErrorResponse(w, r, s3err.ErrNoSuchUpload)