When I wan't to upload a file then I get an exception | Channel was closed

[sm-a]

When I wan't to UploadFile then I get the following exception:
Renci.SshNet.Common.SshException: Channel was closed.
at Renci.SshNet.SubsystemSession.WaitOnHandle(WaitHandle waitHandle, Int32 millisecondsTimeout)
at Renci.SshNet.Sftp.SftpSession.OnChannelOpen()
at Renci.SshNet.SubsystemSession.Connect()
at Renci.SshNet.SftpClient.CreateAndConnectToSftpSession()
at Renci.SshNet.SftpClient.OnConnected()
at Renci.SshNet.BaseClient.Connect()

How can I get rid of this?

Greetings,
Sven

Here my code:

ConnectionInfo conInfo = new ConnectionInfo(smaHost, 22, smaUserName, new AuthenticationMethod[]{
    new PasswordAuthenticationMethod(smaUserName,smaPW)
});

SftpClient sftpClient = new SftpClient(conInfo);
sftpClient.Connect();

string filePath = Path.Combine(ApplicationData.Current.LocalFolder.Path, "mongodb-org-4.2.repo")
sftpClient.UploadFile(SMAReader(filePath), "/etc/yum.repos.d/mongodb-org-4.2.repo", true);

sftpClient.Disconnect();
sftpClient.Dispose();

[sm-a]

I have found the issue. The Server requested for a password change. After password change it works.

Greetings,
Sven