SFTP connection failure - Username/PublicKey combination invalid

If you encounter an “Invalid Username/PublicKey Combination” error while attempting to establish an SFTP connection, you should inspect the server’s authentication log located at /var/log/auth.log (for Ubuntu).

For more information and potential solutions to this issue, we recommend referring to this StackExchange answer: encryption - Ubuntu 22.04 SSH the RSA key isn't working since upgrading from 20.04 - Ask Ubuntu.