Steps to reproduce

1. Try to login with a user the contains a . in the username. I.E p.sandrin

I was able to reproduce it on demoauthor. Username psandrin -> Login successful. Username p.sandrin -> Not able to login

Expected results

The user should be logged into magnolia admincentral

Actual results

The login is not granted. "Error during login. Please try again."

Workaround

Renaming the user without a . dot

Development notes

The Error seems to be caused because the username is parsed as a Regexp pattern. (See appended Stacktrace)