After migrating our site to another host, the OpenID MediaWiki extension stopped working correctly. No one can log in via OpenID anymore.

This message appears on the page when someone tries to log in

Verification error
An error occured during verification of the OpenID URL.

And this appears on the log file:

OpenID: no auth_request

Here's the extension talk page:
http://www.mediawiki.org/wiki/Extension_talk:OpenID#OpenID:_no_auth_request

And here's my message about this on the MediaWiki OpenID Google Group:
http://groups.google.com/group/mediawiki-openid/browse_thread/thread/d8f151c8b96a7293