Outlook 2016 doesn't accept password or app password

The only workaround right now is to go into airplane mode, wait ~30 seconds, and then try again. May need to repeat a couple times. You should stay connected for a while, then when you get the error again just bounce the network again (no need to delete and re-add the account).

MS is working on a fix, no ETA.

Also make sure you have 2factor authentication enabled and are using an app password, not a regular password.

I brought it up because of some other issues that popped up recently

Windows 10 users report app gremlins after Microsoft update (msn.com)

From not the community crew:

Does it have autodiscover DNS record or something related in the microsoft cloud nodes in different countries?

I use quad9 and DNS0eu DOH in windows 11. Outlook 2021 and MFCMAPI are OK (they should use MAPI overt http)

Tried other DNS, such as my ISP, google, cloudflare, and it seems not affected in my device.

I used to got a strange situation that all the folder in the outlook.live.com were missing, and so is the new outlook.
The folder in new outlook were also missing and showed that login required in all 3 outlook.live.com account,
It happened on Jan 15.
They should be on the Microsoft cloud at least in some node.

And each of them became normal around 1,2,3 later week separately in the correspond order of the account creation date, the oldest account became normal last.

(Though the oldest account which created during hotmail period still have no group icon on the left panel in the outlook.live.com on Feb 4.
It was transferred to @live.com suffix at live.com period, and was transferred to @outlook.com suffix at live.com period.
It was randomly seldomly showing the oldest alias while newly got the outlook.com suffix in the new outlook login record windows even I added a new primary alias and unchecked the old aliases for log in. )

By the way, the mapi over http should be better for the outlook 2013 sp1 and exchange 2013 sp1 and later.

https://learn.microsoft.com/en-us/outlook/troubleshoot/connectivity/outlook-not-connect-exchange-use-mapi-over-http
Locate and select the following key in the registry:

HKEY_CURRENT_USER\Software\Microsoft\Exchange

Right-click MapiHttpDisabled and then click Modify.

Change the Value data to 0 and then click OK.

https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/modern-authentication-configuration
https://learn.microsoft.com/en-us/microsoft-365/enterprise/modern-auth-for-office-2013-and-2016?view=o365-worldwide

It is getting worse.

For me it has always allowed me to get emails after many prompts for passwords. But today it will not download any new emaols. So basically it’s useless I log in via a webpage.

Ridiculous this has been happening since 23 Jan and getting worse

Go into airplane mode for a bit (or just disconnect network) then re-enable the network. May have to do it a few times. Seems like some of their servers are fixed and some aren't, and each time you connect you get a different random server.

Thanks but thankfully i have my mobile that can log in with no issues as it logs in rather than uses an app password. The issues i'm having is with the desktop.