Do you see this error message?

• SEC_ERROR_OCSP_INVALID_SIGNING_CERT

There seems to be something wrong on some Microsoft servers. Hopefully they fix this quickly on affected servers.

This looks like a problem with OCSP Stapling on the server because it works when I disable OCSP Stapling in Firefox.

• https://en.wikipedia.org/wiki/OCSP_Stapling
• https://blog.mozilla.org/security/2013/07/29/ocsp-stapling-in-firefox/

You can temporarily toggle this pref to false on the about:config page to disabling OCSP Stapling works for you. It is best to reset this pref via the right-click context menu to true once you are done with the this website.

• security.ssl.enable_ocsp_stapling = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Changing the flag from 'True' to 'False' allowed me to login to both OneNote and OneDrive. I then changed the flag back to 'True' and I could still access these sites, however when I restarted Firefox I could no longer access them so I changed the flag back to 'False'. Hopefully leaving it at 'False' won't cause a security issue.Thank you for your help, it's folks like you that have allowed me to continue using Firefox for years and years.

You can consider to create a user.js file in the profile folder to restore the true setting of the pref, so you would only do set the prefs once to false after a Firefox restart.

• http://kb.mozillazine.org/user.js_file

The user.js file is processed on every start of Firefox.

user_pref("security.ssl.enable_ocsp_stapling", true);

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox