This is a comment on Suddenly A New Problem, posted by WikiAdmin at 11.01.2021 15:29

View source for Re: Chosen user name is invalid

**Solution:**
Please remove the **underline** from your admins username in the installer, then you should be able to login, e.g. ##FfAdmin## or ##ffadmin##.

**Cause:**
The installer does not validate the username against the name pattern, hence it allowed you to insert an underscore in the name.
However the login action validates the username against the allowed pattern. The username must be between 3 and 20 chars long and use **only alphanumeric characters**. Upper case characters are OK.

**Chosen user name is invalid.**
The underscore is not allowed because the username becomes part of the wiki namespace and of the build in ##urls_underscores## option.

**The connection has timed out**
If a user tries to login with wrong credentials, it triggers the function ##log_user_delay()## to mitigate automated brute force attempts.
That might have lead to the connection time out.

**TODO:** 
  1. --validate the username also in the installer against the allowed patterns.-- DONE ((commit:91647c65aa1249e91760f14d03631ca06618a695 Patch))
  1. add non JS form validation