My Yahoo OpenID authentication stopped working today when using IE. It was working for a few months untouched. The application is written in ASP.NET MVC 4 using the DotNetOpenAuth library.
During debugging, I'm noticing that when using IE (testing with version 8-11) on Windows 7, after entering valid Yahoo credentials into the Yahoo OpenID log in page and clicking Submit, 2 responses instead of 1 are sent back to the originating Web server.
They run on separate threads, but one is determined to be valid, and the other is determined to be invalid. Depending on which response is sent back to the user's browsers last, two very different outcomes can happen.
Was this always normal behavior with IE? I've debugged in Chrome and Firefox, and they both only get one response back from the server and are working correctly?