diff --git a/code/go/0chain.net/blobbercore/filestore/storage.go b/code/go/0chain.net/blobbercore/filestore/storage.go
index 74dcf531e..94a503f07 100644
--- a/code/go/0chain.net/blobbercore/filestore/storage.go
+++ b/code/go/0chain.net/blobbercore/filestore/storage.go
@@ -84,18 +84,19 @@ func (fs *FileStore) WriteFile(allocID, conID string, fileData *FileInputData, i
 		return nil, common.NewError("file_seek_error", err.Error())
 	}
 	buf := make([]byte, BufferSize)
-	_, err = io.CopyBuffer(fileData.Hasher, infile, buf)
+	writtenSize, err := io.CopyBuffer(f, infile, buf)
 	if err != nil {
-		return nil, common.NewError("file_read_error", err.Error())
+		return nil, common.NewError("file_write_error", err.Error())
 	}
-	_, err = infile.Seek(0, io.SeekStart)
+
+	_, err = f.Seek(fileData.UploadOffset, io.SeekStart)
 	if err != nil {
 		return nil, common.NewError("file_seek_error", err.Error())
 	}
 
-	writtenSize, err := io.CopyBuffer(f, infile, buf)
+	_, err = io.CopyBuffer(fileData.Hasher, f, buf)
 	if err != nil {
-		return nil, common.NewError("file_write_error", err.Error())
+		return nil, common.NewError("file_read_error", err.Error())
 	}
 
 	finfo, err = f.Stat()
diff --git a/code/go/0chain.net/blobbercore/filestore/tree_validation.go b/code/go/0chain.net/blobbercore/filestore/tree_validation.go
index 2c60acaa9..b44145707 100644
--- a/code/go/0chain.net/blobbercore/filestore/tree_validation.go
+++ b/code/go/0chain.net/blobbercore/filestore/tree_validation.go
@@ -415,6 +415,10 @@ func GetNewCommitHasher(dataSize int64) *CommitHasher {
 }
 
 func (c *CommitHasher) Write(b []byte) (int, error) {
+	if !c.isInitialized || c.fmt == nil || c.vt == nil {
+		return 0, errors.New("commit hasher is not initialized")
+	}
+
 	var (
 		wg      sync.WaitGroup
 		errChan = make(chan error, 2)