Error signing into o365 Web App using Firefox

Issue: Attempting to access the o365 web app using Firefox - after clicking on the user account, you're redirected to a new generic o365 login page.


1. Close the browser tab with the o365 content in it.
2. Open the firefox options / preferences (easiest way is to type into the URL field "about:preferences#advanced" (Without the quotes.)
3. In the "Offline Web Content and User Data" section, remove the two listings:

Should be fixed now.  (Note, it may happen again later.)