Problem

Algorithm negotiation failed.

HRESULT error: FTPLIB_E_SSH_NEGOTIATION (0x80043122)

Cause

The key exchange failed because the client was unable to negotiate a key exchange, encryption, mac, compression or server algorithm with the server.

In most cases, the server only supports legacy, insecure algorithms which are no longer supported by the client.

Solution

Identify the cause by inspecting the log file:

• Enable connection logging
• Locate the connection log file in the log folder: %localappdata%\SmartFTP\Client 2.0\Log\Connection 
• Open a support ticket: menu: File - Help - Request Support
• Attach the .log file to the support email

Take action by upgrading the server software to a newer, secure version.