Firefox loops at office.com login
I cannot login to my office.com accounts with Firefox. Chrome & Edge work fine. Attempting to use Firefox will get me as far as the "Stay signed in?" prompt, then dump me back to the sign in screen: I have refreshed, re-installed, installed a previous version, used Revouninstaller to get rid of all traces of Firefox, deleted the Mozilla folders from the appdata folder and reinstalled + tried using a private window. No joy with anything. I believe this is the key phrase from the error message (quoted below): "client request loop"
Microsoft Sign in
Sorry, but we’re having trouble signing you in. AADSTS50196: The server terminated an operation because it encountered a client request loop. Please contact your app vendor. Troubleshooting details If you contact your administrator, send this info to them. Copy info to clipboard Request Id: e25fd55c-5c0d-4a3e-b932-ee17a8120100 Correlation Id: a5936cb9-243a-486e-b498-d31061e6e534 Timestamp: 2022-08-28T19:07:12Z Message: AADSTS50196: The server terminated an operation because it encountered a client request loop. Please contact your app vendor. Flag sign-in errors for review: Enable flagging If you plan on getting help for this problem, enable flagging and try to reproduce the error within 20 minutes. Flagged events make diagnostics available and are raised to admin attention.
If I try to login @ outlook.office.365.com, I get
500 Something went wrong. UmVwZWF0aW5nIHJlZGlyZWN0cyBkZXRlY3RlZC4gPEJSPjxCUj5DbGljayA8YSBo cmVmPSIvb3dhL2xvZ29mZi5vd2EiPmhlcmU8L2E+IHRvIHNpZ24gb3V0Lg== (Ba se64)
Having a similar issue, except I can log into www.Office.com just fine.
Tested on Mozilla, Chrome and Edge. So far it seems like it's only working on edge oddly enough. Chrome is giving me the same error, so it might be a bigger problem.
You might try disabling any extensions you have and clearing your cookies and cache, this helped me when I was first having issues with the first Office page.
Microsoft has always used a lot of domains for logging in that caused problems with third-party cookies (now referred to as cross-side cookies), so the first to check is for issues with Total Cookie Protection.