Why can't we login to Office 365 after a domain password change when Office.com lets us login with the new password?

(hello Merge, thank you for your question!

I think is an issue with the cached credentials.

Clean up all credentials in "Windows Credentials"
https://support.microsoft.com/en-us/windows/accessing-credential-manager-1b5c916a-6a16-889f-8581-fc16e8165ac0

if that doesn't work then it can be an old installation or "license" on the computer so try to disable it and re-activate the license again:

going into CMD as administrator and run:
for 32 bits OS:

cscript "C:\program files (x86)\microsoft office\office16\ospp.vbs" /dstatus
cscript "C:\program files (x86)\microsoft office\office16\ospp.vbs" /unpkey:XXXX

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for 64 bit OS:

cscript "C:\program files\microsoft office\office16\ospp.vbs" /dstatus
cscript "C:\program files\microsoft office\office16\ospp.vbs" /unpkey:XXXX

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being XXXX the last 5 digits that you get from the /dstatus command

This was tried, and it reset the account, but when he tried to login to it again the same thing happened

Hi Marge,

After trying the above from Jose, I would consider the below if its still not accepting their new credentials:

Are they offsite on VPN working remotely or onsite? Sometimes you have to perform a specific order of steps on a laptop e.g. locking and unlocking the station with the new password in Windows when on VPN via Windows Key + L.

See if this article I made on EE helps, does it say "Need Password" at the bottom of Outlook? Even if it doesn't some of the tips could help, I would also try instaling and using the Microsoft SaRa Diagnostic tool too.

How to Troubleshoot Outlook When It Repeatedly Asks For a Password or Windows Security Field Entries | Experts Exchange |

It does not say need password and he is on-site, not using VPN.  One thing we just found is that his account in the online admin portal has his primary email address listed as the "Company name.onmicrosoft.com" and not his internal email address of username@domainname.com.  It has username@domainname.com listed as the UserName not primary email address.  Looking at other accounts, that is wrong.

I have looked at AD and it shows email as username@domainname.com.

Hello,

Did you verified the Azure AD Signin Logs?
Cheers !

Finally,

Try enabling the ENABLEADAL record on those computers: (using v16 instead of 15)
https://docs.microsoft.com/microsoft-365/admin/security-and-compliance/enable-modern-authentication?view=o365-worldwide

I'm assuming you're in Windows 10, if you are in windows 7 it's a TLS issue
https://support.microsoft.com/topic/actualizar-para-habilitar-tls-1-1-y-tls-1-2-como-protocolos-seguros-predeterminados-en-winhttp-en-windows-c4bd73d2-31d7-761e-0178-11268bb10392

Have they changed their password successfully in the past or this is the first time? Have you tried creating a new mail profile for Outlook or that errors\fails?

admin portal has his primary email address listed as the "Company name.onmicrosoft.com" and not his internal email address

That should be it.  Somehow that must have changed.  If he logs in with his onmicrosoft.com account, it would probably work. By adding back the original account (internal) I would expect that to work and just remove the onmicrosoft.com account so he does not get confused.

I have added the alias back into the Attribute Editor in Active Directory and it has synced to the Online Portal.  It now shows his primary account correctly and the other account as his alias.  As soon as he gets back with me I will have him try it to see if he can log in now.

I have gotten back with him.  I added his SMTP:username@domainname.com to the attibutes editor on his account in AD and let it sync.  His phone is now working again, but still can't login to the account.  It comes up with his emails and it is working, but it won't activate his account and says that not all of the features will work until he activates it.  We think at this point it is something on his computer.  I had him login to another system and it is working fine.

Thank you for your help.

Did you try the SaRa Diagnostics tool, it may find errors or help isolate what's wrong to fix the activation? I would also try also Microsoft's "scrubbing uninstaller" tool as well not just a manual uninstall\reinstall. It could be something with app data or cached info.

See the diagnostic tool:
https://docs.microsoft.com/en-us/outlook/troubleshoot/performance/how-to-scan-outlook-by-using-microsoft-support-and-recovery-assistant

See option 2-
https://support.microsoft.com/en-us/office/uninstall-office-from-a-pc-9dd49b83-264a-477a-8fcc-2fdf5dbf61d8

Possibly you could as a last resort create a new OS profile and migrate his data too, or test if Outlook is fine in a new Windows profile on the system.

What is the OS that you're using? windows 7 8 8.1 10?

Then basically it was an issue with the computer's profile.

He has re-created his profile and everything is now working great.  Strange how a password change caused all of these issues.  Thank you for your help!!

OK Marge Thank you for clarifying!