Outlook User/Password Prompt

Question

Hello,

After some time searching I now have to post my question here.

We are currently in the process of migrating the Exchange accounts from on-prem to Exchange Online. We now have the annoying problem that the Outlook login window keeps asking for login details. This apparently happens when an account from the cloud accesses an on-prem account and vice versa. Unfortunately, setting “AlwaysUseMSOAuthForAutodiscover” to 1 in the registry doesn’t help. Modern authentication is activated on both on-prem and cloud. The tests on MS's test connectivity page look okay. But we can't get rid of it.

If I turn off cache mode, the pop-up doesn't appear, probably because nothing is being synchronized in the background.

On the on-prem side there is an Exchange 209 with CU13.

I hope someone here has an idea. We can always click away from the popup and then Outlook will connect again, but it's just very annoying.

Answer 1

Hi @Jörg Mai,

Thank you for posting to Microsoft Community. We are happy to help you.

Based on your description, I understand the issue is the Outlook continually prompts for login. However, I am confused about what you said about “the cloud accesses an on-prem account and vice versa”. Could you kindly explain it to me for understanding and helping you better.

The login prompt issue can be caused by a variety of factors, including incorrect login credentials, outdated software, or a corrupted Outlook profile. Exclude attempts you've already made. You could perform comprehensive troubleshooting such as the following.

• Corrupt Outlook Profile. Corrupt profile may cause Outlook to no longer remember your password. Please try to create a new mail profile in Control Panel and reconfigure your email account in the new profile to fix the issue. Create an Outlook profile - Microsoft Support.
• Kindly run Microsoft Support and Recovery Assistant (SaRA Tool) About the Microsoft Support and Recovery Assistant - Microsoft Support
• Launch Outlook in Safe Mode as following link Open Outlook in safe mode - Microsoft Support. This will disable any add-ins that may be causing the issue.
• Disable the Always prompt for login option in Outlook.
• Incorrect credential cached in Credential Manager. If the cached credentials are incorrect, you will be prompted for password. Try to remove incorrect credentials from the Credentials Manager.

Also, could you kindly share the login prompt screenshot for the further investigation.

If there are anything else you need help, please feel free to reply to me.

Answer 2

Did you clear the cached credentials from Control panel for the user account?

As a test, can you edit the hosts file and add the Autodiscover record for exchange online and see if you still get any popups?

Also Corrupt profile may cause the problem, try to recreate OST file. If it can fix the issue.

Answer 3

This is a known issue that can occur during a hybrid deployment of Exchange on-premises and Exchange Online.

1. Sync all user accounts even there are on-prems users then you will see it gets resolved.
2. Clear cashed credentials

Good Luck!