Duo "500: Internal Server Error" in Firefox


I reinstalled Windows and I'm no longer able to complete the Duo Prompt in Firefox. I receive "500: Internal Server Error" after authenticating with my Directory ID and passphrase at the Central Authentication Service (CAS). 


Duo Multi-Factor Authentication (MFA).


Contact the IT Service Desk for assistance resolving this issue. Alternatively, wait a maximum of 5 days, and the issue will resolve itself. In the meantime, you should be able to authenticate using a different web browser. 


The Duo Prompt is remembering your device from before you reinstalled Windows.