Our generic message of 'authentication failed' is most likely not cutting it anymore.

Watching the esgf mailing list, several users (a week) complain that they are not able to access data because of 'authentication failed' messages during openid login.

I feel that we should improve our messaging during login to help our users diagnose their own login problems better.

For instance, I feel that if a server is unreachable, down for maintenance, or there is a certificate issue (due to lack of trust), we should say so.