Outlook 2016 doesn't accept password or app password

First authentication error in 2 days on my outlook.com emails (2 accounts() on my android email client (9Folders). Still not fixed.

"Overly dramatic"? Ad hominems are not helpful. Four posts in a row is overtly excessive. For your part you seem to have taken it upon yourself to hijack and dominate this thread apparently feeling a need to respond to each and every post, while adding no new information that hasn't already been stated; i.e. repetition. People use all sorts of software and devices, and while you claim to have a configuration that works for you as you have been repeating over and over, it may not be available to others, while the configurations and same authentication technologies that are problematic with MS are not with other major providers using the same clients. If you have something new to add, great, but otherwise feeling a need to reply to every post while repeating yourself is, frankly, annoying when trying to follow the thread and allow other voices to be heard.

If I may make a suggestion, everyone needs to scroll to the bottom of the issue page and click the button for "not helpful" and then provide the feedback it's been too long without update.

I happen to know when any of their articles gets more negative feedback than expected it raises an internal flag that may get more attention for us.

Outlook and other apps are unable to connect to Outlook.com - Microsoft Support

This problem is so widespread that every platform and every MS employee would have experienced it already. Of course, there is possibility that MS employee themselves do not use Hotmail, they know better :)

What is broken is IMAP connections. Most businesses use the new OAuth through an Exchange Server setting so the MS people are getting & sending email just as happy as can be. I found that the built in Windows 10 Mail program will allow me to connect that way, but OAuth is blocked for 3rd party apps fpr the free outlook.com emails. That is why, in my opinion, this is not a critical issue for them as it "only" breaks people who use the free version. For those that pay for Microsoft 365, you should be able to connect via OAuth - I know Mailbird can handle that.

Me and the wife are having the same issue.

I use BlackBerry Hub on Android, started prompting at the start of the week. Managed to get it going using different server URLs for a short time, e.g. outlook.com, outlook.office365.com, hotmail.com, microsoft.com with varying degrees of success. Outlook.live.com seemed to work for a few hours then got the same error.

Wife just uses native iOS mail client and is also prompted for password.

Utter shambles, considering moving away from Microsoft for mail. Wasn't keen on Google but at least I wasn't stuck without mail on my phone for a week.