Steps to replicate the issue:
- Log in to your account
- Go to Special:CreateAccount (Will redirect from https://en.wikipedia.org/wiki/Special:CreateAccount to https://auth.wikimedia.org/enwiki/wiki/Special:CreateAccount)
- While you are on the Special:CreateAccount page, try using the search box (for example search about Wikimedia Foundation)
Note: This applies to all Wikimedia projects, not just the English ones.
What happens?:
https://auth.wikimedia.org/enwiki/w/index.php?search=Wikimedia+Foundation&title=Special%3ASearch&go=Go
Permission error.
You do not have permission to read this page, for the following reason:
You are not allowed to execute the action you have requested.
What should have happened instead?:
Either display search results related to the Wikimedia Foundation, or open the article directly.
It appears that the bug (?) is that the account creation is associated with "auth.wikimedia.org", which is a separate domain from the Wikipedia itself.