Fix Usernames can contain lowercase and numbers in WP.
Hey! I am using WordPress for my blogging platform for 5 years. But recently I have installed WordPress Multisite. I have installed a forum with a subdomain. But the problem is When I (Site Administrator) want to create a new user from the admin account it says “Usernames can only contain lowercase letters (a-z) and numbers.” That means I can’t use the uppercase letter in the username field. And it’s happening only from the backend administrator account while creating a new user. But it is not happening in the front end of the forum while creating a new account. Is it possible to fix this error?
If someone can help me. Thanks in advance!