Username with Cyrillic charset doesn't supported in 2.1.3... (Bugs)
After update from 2.1.1 to 2.1.3. previously registered users with cyrillic symbols in their usernames can't login to forum. Error message "The user name contains invalid characters" appears... :(
How can I fix the problem?
This check is only performed when registering. New user names are checked for some control characters. This is done by the function contains_special_characters() (includes/functions.inc.php). What happends if you change it like this?
function contains_special_characters($string) { return false; }