You are using Office 365 and you turn on your PC and open Outlook but discover that Outlook requires a password. The message "Need Password" is staring at you from the info bar at the bottom of the Outlook window.
You click to try and input your password, but it quickly pops up then the password dialogue box disappears. So how do you fix it?
I've used numerous different methods on various machines that worked, so I thought I'd document them here for you so you don't have to waste the time I did researching the issue. I've also included some unconfirmed options for you to try based on advice from some colleagues that have had success with other approaches. Please note that these unconfirmed options are based on third party suggestions, rather than first hand experience.
Just deleting the the Outlook profile doesn't work, so don't waste your time.
Close Outlook down. Then open Word and and select a blank document. Then click File > Account > Sign Out. Close Word down. Now open Outlook and you should get the Username and Password prompts.
Add a DWORD called DisableADALatopWAMOverride with a value of 1 to the registry in the path below:
Once done, reboot your PC. When your PC has rebooted open Outlook and all should be good with the world. If it didn't work, ensure you remove the registry entry you created earlier and reboot again.
Ensure Outlook and any other Office applications are closed.
In Windows 10 open settings by using Windows + I keys simultaneously and the Settings screen will open. Click System > Shared Experiences. If the Accounts section shows an error with the credentials, input the correct credentials. Once you've applied the correct credentials, open Outlook and things should be back to normal.
Method 4 (the most drastic method):
If you've tried all the options above and none work, the final method is to nuke the users PC profile. This is a drastic and destructive solution, but it definitely works because it creates a totally new and clean profile for the user. Please remember to backup the profile before you delete it, just in case.
If you're not sure how to nuke a users profile a detailed explanation can be found here...
Method 5 (unconfirmed):
I have read but can't confirm that running system file checker to ensure there isn't any file corruption rectifies the issue. It's simple to run, just open a command prompt in admin mode, then run:
Wait until the scan completes and reboot the PC.
Method 6 (unconfirmed):
A colleague mentioned that he had success by disconnecting the Work or School account in Windows Settings. To do this, use the following method. First close down Outlook. Hold the Windows + I keys simultaneously to open the Settings window. Then click Accounts > Access work or school to open the accounts settings options.
Now highlight the account you're having issues with and click Disconnect. Once done, open Outlook and you should now be prompted for your username and password.
Method 7 (unconfirmed):
I have had colleagues claim that repairing your installation of Office can rectify the issue. Open Control Panel > Programs and Features and scroll down to find your installation of Office 365. Highlight Office 365 and select Change. Now choose repair Office. Once complete, reboot your PC.
Method 8 (unconfirmed)
Force a password change via the O365 admin portal or if using Azure AD Connect, via your Active Directory User and Computers MMC console. This was suggested to me by a friend and because I haven't had a client experience this issue for a while, I haven't had the opportunity to test whether this works.
Hope you've found this some what useful...