I set up a project on my main domain example.com and then moved it to a subdomain sub.example.com
Now when I try to use the same (default ASP.NET MVC or on my Discourse forum) project with OpenId and click on the Google button to log in with my Google account it throws the following error -
That’s an error.
OpenID auth request contains an unregistered domain: http://sub.example.com
I have tried Googling that message but apparently I am one of the first four people to see it. Any ideas here?
According to this page, Google closed registration to new OpenID 2.0 clients in May 2014 and will be shutting down the OpenID 2.0 service in April 2015.
The reason why some hosts work and some don't is that although Google isn't adding new hosts, you can still use the ones that are already registered.
UPDATE : Some people have asked for a simple explanation for how to fix this, or otherwise how to proceed.
Basically, you now have 2 options.
Use OAuth 2.0 (instead of openID protocols and older versions of OAuth)
or
Use Google+ login (which Google tried to "push" you towards)
For more details check the migration guide :