fix

iOSClient/Networking/NCNetworking.swift

@@ -463,7 +463,7 @@ import Alamofire
                                         
             } else {
                 
-                NCManageDatabase.sharedInstance.setMetadataSession(ocId: metadata.ocId, session: "", sessionError: errorDescription, sessionTaskIdentifier: 0, status: Int(k_metadataStatusUploadError))
+                NCManageDatabase.sharedInstance.setMetadataSession(ocId: metadata.ocId, session: nil, sessionError: errorDescription, sessionTaskIdentifier: 0, status: Int(k_metadataStatusUploadError))
                 
                 NotificationCenter.default.postOnMainThread(name: k_notificationCenter_uploadedFile, userInfo: ["metadata":metadata, "errorCode":errorCode, "errorDescription":errorDescription])
             }