error code 4 when I try to upload a file via sftp

[ahoelzemann]

I'm try to upload some data from my the smartphone to a server via sftp.
However, I keep on receveing an exception with the error code 4. The error message is only "failure", so it's pretty hard for me to understand what is going on.

I'm able to connect to the server and to create folders, but the upload itself is not working. The code itself is copied from your readme page. Both variables, serverPath and localFilePath are valid paths.

    final file = await sftp.open(serverPath, mode: SftpFileOpenMode.create | SftpFileOpenMode.write);
     await file.write(File(localFilePath).openRead().cast());

thank you and best regards.

[ahoelzemann]

Dart Version 2.16.1
Flutter Version: 2.10.1

I will attach the corresponding exception

flutter: SftpStatusError: Failure(code 4)
flutter: SftpStatusError: Failure(code 4)
flutter: #0      SftpClient.open (package:dartssh2/src/sftp/sftp_client.dart:63:5)
<asynchronous suspension>

[xtyxtyx]

The OpenSSH SFTP server use 'Failure' message for many errors and it's hard to tell the specific reason. This usually happens when the permissions is not enough, or the filesystem is read-only.
Does your account have enough permission to write to the remote destination?

[ahoelzemann]

Hey, thank you very much for quick answer!
permission is granted, I also tried out the admin user of the server. Do you have another idea?

[xtyxtyx]

Currently I have no other ideas about the error. However it may help to inspect the logs from sftp-server and see what actually happened. Detailed instructions can be found here: https://access.redhat.com/articles/1374633.

[ahoelzemann]

Thanks for the help @xtyxtyx . I don't get any specific error message.

It seems like the session closes immidiately.

Mar  6 18:35:01 xxxxxxx CRON[2024678]: pam_unix(cron:session): session opened for user root by (uid=0)
Mar  6 18:35:01 xxxxxxx CRON[2024678]: pam_unix(cron:session): session closed for user root

Do you have any idea?