When I try to login to the Stack Exchange Data Explorer using Stack Overflow, it fails with the following error message:
StackApps authentication failed
I've tried several browsers, and even in incognito mode it's not working so it can't be a cookie problem. Also when I try to login with a sockpuppet account, which hasn't logged in before, it asks for permission (which is expected) but then fails with the same error message.
https://stackexchange.com/oauth/access_tokenand that returns me a certificate has expired.