Unable to log in using Google Apps due to error "Unexpected error in the authentication system."
A user tries to log in using Google and after he/she clicks the 'Log in using Google' button the following error appears:
Unexpected error in the authentication system.
- One of the possible causes may be because there is a user already created on the application which username is the full email address, instead of just the part before the @ sign.
- Another cause is when the username and its email address (the part before the @ sign) doesn't match, i.e.
In the example above, when the user logs in with Goggle using the email firstname.lastname@example.org, JIRA will check if there's already a username 'testing'. If the username 'testing' doesn't exist, JIRA will automatically try to create it, however, this operation will fail because because there is another username which email is 'email@example.com'.
Edit this user's details and change its username removing the '@example.com' part.