diff --git a/commons/bundletransfer.go b/commons/bundletransfer.go
index 8659edd..a437da6 100644
--- a/commons/bundletransfer.go
+++ b/commons/bundletransfer.go
@@ -21,7 +21,7 @@ import (
 const (
 	MaxBundleFileNumDefault  int   = 50
 	MaxBundleFileSizeDefault int64 = 1 * 1024 * 1024 * 1024 // 1GB
-	MinBundleFileNumDefault  int   = 5
+	MinBundleFileNumDefault  int   = 3
 )
 
 const (
@@ -877,73 +877,48 @@ func (manager *BundleTransferManager) processBundleUpload(bundle *Bundle) error
 			manager.progress(progressName, 0, totalFileSize, progress.UnitsBytes, false)
 		}
 
-		var asyncErr error
-		wg := sync.WaitGroup{}
-
-		for fileIdx := range bundle.files {
-			// this is for safe access to file in the bundle array
-			file := bundle.files[fileIdx]
-			wg.Add(1)
-
-			go func(progressIdx int) {
-				defer wg.Done()
-
-				var callbackFileUpload func(processed int64, total int64)
-				if manager.showProgress {
-					callbackFileUpload = func(processed int64, total int64) {
-						fileUploadProgressMutex.Lock()
-						defer fileUploadProgressMutex.Unlock()
-
-						fileUploadProgress[progressIdx] = processed
-
-						progressSum := int64(0)
-						for _, progress := range fileUploadProgress {
-							progressSum += progress
-						}
-
-						manager.progress(progressName, progressSum, totalFileSize, progress.UnitsBytes, false)
-					}
-				}
+		for fileIdx, file := range bundle.files {
+			var callbackFileUpload func(processed int64, total int64)
+			if manager.showProgress {
+				callbackFileUpload = func(processed int64, total int64) {
+					fileUploadProgressMutex.Lock()
+					defer fileUploadProgressMutex.Unlock()
 
-				if !ExistsIRODSDir(manager.filesystem, path.Dir(file.IRODSPath)) {
-					// if parent dir does not exist, create
-					err := manager.filesystem.MakeDir(path.Dir(file.IRODSPath), true)
-					if err != nil {
-						if manager.showProgress {
-							manager.progress(progressName, -1, totalFileSize, progress.UnitsBytes, true)
-						}
+					fileUploadProgress[fileIdx] = processed
 
-						err = xerrors.Errorf("failed to create a dir %s to upload file %s in bundle %d to %s: %w", path.Dir(file.IRODSPath), file.LocalPath, bundle.index, file.IRODSPath, err)
-						logger.Error(err)
-						asyncErr = err
-						//return err
-						return
+					progressSum := int64(0)
+					for _, progress := range fileUploadProgress {
+						progressSum += progress
 					}
 
-					ClearIRODSDirCache(manager.filesystem, path.Dir(file.IRODSPath))
+					manager.progress(progressName, progressSum, totalFileSize, progress.UnitsBytes, false)
 				}
+			}
 
-				err := manager.filesystem.UploadFileParallel(file.LocalPath, file.IRODSPath, "", 0, manager.replication, callbackFileUpload)
+			if !ExistsIRODSDir(manager.filesystem, path.Dir(file.IRODSPath)) {
+				// if parent dir does not exist, create
+				err := manager.filesystem.MakeDir(path.Dir(file.IRODSPath), true)
 				if err != nil {
 					if manager.showProgress {
 						manager.progress(progressName, -1, totalFileSize, progress.UnitsBytes, true)
 					}
 
-					err = xerrors.Errorf("failed to upload file %s in bundle %d to %s: %w", file.LocalPath, bundle.index, file.IRODSPath, err)
-					logger.Error(err)
-					asyncErr = err
-					//return err
-					return
+					return xerrors.Errorf("failed to create a dir %s to upload file %s in bundle %d to %s: %w", path.Dir(file.IRODSPath), file.LocalPath, bundle.index, file.IRODSPath, err)
 				}
 
-				logger.Debugf("uploaded file %s in bundle %d to %s", file.LocalPath, bundle.index, file.IRODSPath)
-			}(fileIdx)
-		}
+				ClearIRODSDirCache(manager.filesystem, path.Dir(file.IRODSPath))
+			}
+
+			err := manager.filesystem.UploadFileParallel(file.LocalPath, file.IRODSPath, "", 0, manager.replication, callbackFileUpload)
+			if err != nil {
+				if manager.showProgress {
+					manager.progress(progressName, -1, totalFileSize, progress.UnitsBytes, true)
+				}
 
-		wg.Wait()
+				return xerrors.Errorf("failed to upload file %s in bundle %d to %s: %w", file.LocalPath, bundle.index, file.IRODSPath, err)
+			}
 
-		if asyncErr != nil {
-			return asyncErr
+			logger.Debugf("uploaded file %s in bundle %d to %s", file.LocalPath, bundle.index, file.IRODSPath)
 		}
 	}