Limit Usernames
 

How can i limit usernames in 3.6.5 to only contain characters from A - Z and 0 - 9 and replace spaces with underscores?

AdminCP -> vBulletin Options -> User Registration Options -> Username Regular Expression

See admin help for examples.

I looked through admin help and on the net for examples, but it doesnt work. I'm getting the syntax wrong. Does preg_replace work in that field too?

Just click on the Question Mark behind the field.

I did, it takes me to a page with preg_match, but doesnt say if preg_replace can be used too.

Ah, i see what you mean now. I didnt click the ? graphic, i clicked the text link. It works now though.

The "?" is where the admin help is located. ;)