Thread:Project:Support desk/DoPOST when selecting Add User from Special:UserAdmin - No Special Page when attempting to add user from "Add User" special page/reply (4)

I think we talk about https://www.mediawiki.org/wiki/Extension:UserAdmin ?

Then the "the ?/& issue" seems to be this one: https://www.mediawiki.org/wiki/Extension_talk:UserAdmin#No_such_special_page_26033

If you see the "No special page" error, what is the URL of the site?