Outlook 2016 doesn't accept password or app password

I have been running tests on my testbed devices. One approach is to run GMail or Apple Mail for all non-MS accounts, and isolate MS accounts to Outlook for Android/iOS. The problem is you will have two sets of mail apps and calendar apps. I did power consumption monitoring and you definitely see an increase in power consumption where both apps are doing their own syncing. It's not a very pretty setup. In comparison, Outlook seems to consume more power than Google Contacts/GMail/Calendar combined.

Maybe the next step is to start moving those usage off Microsoft systems. My earlier (years ago) reasons for using Microsoft is my work travel to China where Google apps are blocked. However, I have had free roaming on my phone, so Google apps will work, so at least email and calendar sync can happen.

I also saw an article that MS will not depreciate Outlook "Classic" until 2029. I think they know the "new Outlook" has long ways to go before it can come close to the current Outlook.

There is no solution and based upon previous MS behaviour won't be any. I think MS don't care and sadly it hits where it hurts the most. MS Outlook and such was tool so many use. Is it worth shelling for new subscription or you will find other solution is up to you. Confusion also arises from same problem been reported before and for that time these solutions worked. This time it is another thing. So no registry change will help. Shame... i agree with that.

Agreed. Useless, and just a real CF caused by MS. Shame!

I've done it a dozen times just now - useless.

I have been looking at this issue from Outlook desktop. I think when you get a password prompt, you could be getting 4 to 5 of them in a row.... I think you should answer all of them until it stops prompting you. By looking the connection status, it appears Outlook would open 4 to 5, even up to 6 or 7 parallel sessions. I assume each session is for syncing/managing different type of data. I think when the server blocks you, it's blocking each of those sessions separately. If you entered your password, you'd have to do it multiple times, each satisfy one of the sessions. Once done, at least for me, Outlook desktop goes quiet for many hours.