What ssh key format is required?

BrettJ

I am evaluating MySQL Compare and I am trying to connect to two separate database servers over ssh using public/private key pair. When I try to do the compare, I get an error message

  Cannot connect to server on HOSTNAME:

  Wrong Key Format.

What key format is this application looking for? In the browse dialog window to select the key it's looking for files with a ".key" extension. The private key I create using the Windows 11 Pro ssh-keygen program doesn't have any extension (i.e. id_rsa). I have also tried using Putty's putty-keygen to convert the private key to a ".ppk" format. Neither of these private keys seem to work, both throwing the same "Wrong Key Format" error.

I have never seen a private key use a ".key" extension, so I'm not certain how I would create this type of key, and I can't find anything in the documentation that describes what type of key it's looking for.