Currently, if you create a user with a name field containing special characters like parenthesis, the GUI shows no error at all and the user creation seems to be successful.

However, the user never receive their login email because of this hidden error. This error can be seen if trying to reset the user's password. This is documented here https://my.f5.com/manage/s/article/K000153135, but this problem could be avoided by providing clear GUI feedback on user creation errors.