Did not find mosh server startup message

If you have just installed Mosh server and tried to connect to it, you might have run into the following error:

$ mosh user@server
/usr/bin/mosh: Did not find mosh server startup message.

This happens when your SSH session sends a locale that Mosh does not support. The fix is fairly easy, just configure your SSH not to send the LANG variable. To do that, open your /etc/ssh/ssh_config and comment out the following line:

# SendEnv LANG LC_*

That’s it, now you can use your Mosh without any hiccups.