ae537c6 created the issue

After you fixed #8597, I could login for a little while on my SSH, it was flaky but it worked. Now I again get the same message:

Change of username or service not allowed: (<>,ssh-connection) -> (,ssh-connection). Please contact your web hosting service provider for assistance.

I have private/public key + google authenticator. With the terminal-ssh on OSX this works fine, but not with Cyberduck.

I fill in my username in the "open connection" dialog, check "use public key authentication". Click connect and then fill in the passphrase to the key (here the username is remembered). Clicking 'Login' again I now get a "partial authentication success" dialog, where the username is empty and I have to fill in a password (which is weird, since I don't get this for the terminal-ssh).
I tried entering the verification code (from google authenticator), but it doesn't work.

/// Since #8597 I've removed the need for password during login, now it's only key- and authenticator