How do I limit the username field upon registration to A-Z and 0-9 for single site? So no spaces, hyphens, underscores, dots etc.
I need to know what the wp specifications for the usernames are. Like allowed minimum and maximum length, are special characters like ü,ö,ä,ß accepted,..? Unfortunately I couldn't find any insight on ...
I want to create a user account on my multi-site installation of Wordpress with a username less than 4 characters. But since Wordpress has a limit of usernames at least being 4 characters, this error ...