Sorry, but this username has already been taken.

So I finally finished creating a forum page for my friend who is going to run a private server and I tried making an account of my own and giving him the Admin one but it says that the username I'm trying to use is taken. Only about 6 people have registered and no one has that username. I tried using a different email and it does the same. My other friend is also having this problem registering with the username he wants to use. Mine is "AncientJewel" his is "Vale". Can anyone tell me what I can do to fix this please?

Hello,

Adjust this option:
Admin Panel > General > Security:
Unauthorize subscriptions made with the most commonly used spam usernames: Set it to 'No'
> Save

Also, check if the user has already been registered by activating it here:
Admin Panel > Users & Groups > Inactive Users > Activate the user there

Omgosh you're the best! Thank you so very much (: It worked like a charm, keep up the great work.