SFTP connexion not working anymore

Posted January 21, 2015 2.9k views

Hello I have a problem. I followed this tutorial :

It was working for months but since a week it’s not working anymore. I haven’t change anything and I’m not able to understand what’s happening through Filezilla’s log. Here it is.

Response:   fzSftp started
Trace:  CSftpControlSocket::ConnectParseResponse(fzSftp started)
Trace:  CSftpControlSocket::SendNextCommand()
Trace:  CSftpControlSocket::ConnectSend()
Command:    keyfile "C:\Users\Aurélien\my_keys\gg_private.ppk"
Trace:  CSftpControlSocket::ConnectParseResponse()
Trace:  CSftpControlSocket::SendNextCommand()
Trace:  CSftpControlSocket::ConnectSend()
Command:    open "" 22
Trace:  Looking up host ""
Trace:  Connecting to port 22
Trace:  We claim version: SSH-2.0-PuTTY_Local:_Jan__7_2015_14:17:27
Trace:  Server version: SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2
Trace:  We believe remote version has SSH-2 channel request bug
Trace:  Using SSH protocol version 2
Trace:  Doing ECDH key exchange with hash SHA-256
Trace:  Host key fingerprint is:
Trace:  ecdsa-sha2-nistp256 d5:e8:ca:a6:69:ae:dd:68:21:07:1d:17:c7:48:86:9b
Command:    Trust new Hostkey: Once
Trace:  Initialised AES-256 SDCTR client->server encryption
Trace:  Initialised HMAC-SHA-256 client->server MAC algorithm
Trace:  Initialised AES-256 SDCTR server->client encryption
Trace:  Initialised HMAC-SHA-256 server->client MAC algorithm
Trace:  CControlSocket::DoClose(64)
Trace:  CSftpControlSocket::ResetOperation(66)
Trace:  CControlSocket::ResetOperation(66)
Error:  Could not connect to server
Trace:  CFileZillaEnginePrivate::ResetOperation(66)
Status: Waiting to retry...

It seems to be a server problem as stated here
Trace: We believe remote version has SSH-2 channel request bug

Thanks for the help you could bring me.

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

Submit an Answer
1 answer

Can be. But you can’t completely blame the server. There are multiple solutions for this

  1. Update your putty
  2. Modify ‘Algorithm Selection policy’ (In putty, Connection > SSH > Kex) in putty. Some policy may not work with the server. You need to change the order in it. 'Diffie-Helman group 14’ or 'Diffie-Helman group exchange’ on the top will normally work.

Most of the cases these worked for me.