diff --git a/weed/filesys/page_writer/upload_pipeline.go b/weed/filesys/page_writer/upload_pipeline.go
index 0c9e13649..b87061adb 100644
--- a/weed/filesys/page_writer/upload_pipeline.go
+++ b/weed/filesys/page_writer/upload_pipeline.go
@@ -142,9 +142,10 @@ func (cw *UploadPipeline) moveToSealed(memChunk *MemChunk, logicChunkIndex Logic
 	cw.sealedChunksLock.Unlock()
 
 	cw.writers.Execute(func() {
+		// first add to the file chunks
 		cw.saveOneChunk(sealedChunk.chunk, logicChunkIndex)
 
-		// remove from sealed chunks
+		// then remove from sealed chunks
 		sealedChunk.FreeReference()
 		cw.sealedChunksLock.Lock()
 		defer cw.sealedChunksLock.Unlock()
@@ -162,6 +163,9 @@ func (cw *UploadPipeline) moveToSealed(memChunk *MemChunk, logicChunkIndex Logic
 }
 
 func (cw *UploadPipeline) saveOneChunk(memChunk *MemChunk, logicChunkIndex LogicChunkIndex) {
+	if cw.saveToStorageFn == nil {
+		return
+	}
 	for t := memChunk.usage.head.next; t != memChunk.usage.tail; t = t.next {
 		reader := util.NewBytesReader(memChunk.buf[t.StartOffset:t.stopOffset])
 		cw.saveToStorageFn(reader, int64(logicChunkIndex)*cw.ChunkSize+t.StartOffset, t.Size(), func() {
diff --git a/weed/filesys/page_writer/upload_pipeline_test.go b/weed/filesys/page_writer/upload_pipeline_test.go
new file mode 100644
index 000000000..81191868f
--- /dev/null
+++ b/weed/filesys/page_writer/upload_pipeline_test.go
@@ -0,0 +1,47 @@
+package page_writer
+
+import (
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"testing"
+)
+
+func TestUploadPipeline(t *testing.T) {
+
+	uploadPipeline := NewUploadPipeline(nil, 2*1024*1024, nil)
+
+	writeRange(uploadPipeline, 0, 131072)
+	writeRange(uploadPipeline, 131072, 262144)
+	writeRange(uploadPipeline, 262144, 1025536)
+
+	confirmRange(t, uploadPipeline, 0, 1025536)
+
+	writeRange(uploadPipeline, 1025536, 1296896)
+
+	confirmRange(t, uploadPipeline, 1025536, 1296896)
+
+	writeRange(uploadPipeline, 1296896, 2162688)
+
+	confirmRange(t, uploadPipeline, 1296896, 2162688)
+
+	confirmRange(t, uploadPipeline, 1296896, 2162688)
+}
+
+// startOff and stopOff must be divided by 4
+func writeRange(uploadPipeline *UploadPipeline, startOff, stopOff int64) {
+	p := make([]byte, 4)
+	for i := startOff / 4; i < stopOff/4; i += 4 {
+		util.Uint32toBytes(p, uint32(i))
+		uploadPipeline.SaveDataAt(p, i)
+	}
+}
+
+func confirmRange(t *testing.T, uploadPipeline *UploadPipeline, startOff, stopOff int64) {
+	p := make([]byte, 4)
+	for i := startOff; i < stopOff/4; i += 4 {
+		uploadPipeline.MaybeReadDataAt(p, i)
+		x := util.BytesToUint32(p)
+		if x != uint32(i) {
+			t.Errorf("expecting %d found %d at offset [%d,%d)", i, x, i, i+4)
+		}
+	}
+}