'''Hello shuzihank''' I use this same version of firefox, and I can use outlook without any problem, but if you are having this problem, I suggest you try to reinstall firefox, remembering that this problem may be on your computer and not on firefox. Signed Luis Davi

Hi shuzihank, that's not a very useful error message, is it. Does that occur before the sign-on screen, during sign-on, or when redirecting back to the Inbox? I know some features of the site don't work properly without cookies and local storage being fully enabled. For example, because I use the "Delete cookies and site data when Firefox is closed" setting, I needed to create an exception (using the button to the right of it) for the various Outlook sites (outlook.live.com, outlook.office.com, outlook.office365.com). <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-05-16-11-00-51-5c56d7.png"> <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-05-16-11-01-32-e4f0ba.png">