What security software are you running? Windows home or pro? Let me login...

I'm in with no issues. see screenshot When what the last time you changed your password? I assume you have the app on your phone. I would try changing your password.

Also recommend you turn on 2FA because I get a few notifications a day that someone is trying to log into my account from several places. see screenshot

Thanks jonzn4SUSE. I am on a laptop, WIndows 11, only login to Outlook from Firefox is affected, only since latest update. My password is OK from ex. Chrome and Pop Peeper logins. I use Malwarebytes, but disabled it for testing the issue. Also tried all recommendations from past incarnations of this problem. I don't want to set up 2FA until this is resolved to avoid introducing further variables.

After entering Outlook credentials (username and password) I get a page with just this message:

Please retry with a different device or other authentication method to sign in. For more details, please see this link

and the link goes to a page starting:

Error 400 when signing in (followed by advice on logging in, none of which helped)

...again, only from Firefox, latest upgrade 147.0.1, as of today 1/16/2026

Yes, I was getting that a few weeks ago and finally changed my password(3yrs since last change) and now the process is smooth. I'm in it everyday, been using from 97. I know changing the password is a pain, but just add a few different things to update it.

Verified password works AOK in Chrome, Opera, Pop Peeper. Not a password problem, a Firefox problem, just since latest upgrade 147.0.1, today 1/16/2026