If I'm on http://ask.libreoffice.org/en/account/signin/?next=/en/, I click on OpenID and then enter https://openid.stackexchange.com and click Log In, I get a page that says:
An error occurred on the server
This event has been recorded.
If you believe you encountered this message in error, please report it.
I clicked report it and here I am reporting it! Using Firefox 26