I'm working on a local server setup, using an old-school sign-in method with initials and a domain through Windows. We don't use Office 365 at all. I have a genuine copy of Office 2024 registered with my email, and I can access my account on Microsoft's website without any issues. My email is properly set up using the control panel, and I can access my emails and calendar through the OWA portal just fine.
However, Outlook constantly prompts me with a 'Microsoft sign-in' request that I can't dismiss. If I try to close the prompt, Outlook shows a message saying it 'needs a password,' and clicking on it just brings the prompt back up. The credentials it's asking for don't seem to work, and I have no clue what password it's requesting. This issue has been a significant frustration for me, especially since I'm the only one in the office who's experienced this problem. I've restored my computer several times, and no matter what I try, I'm hounded by these prompts related to Office 365, even though we've never used it.
When attempting to log in through the Microsoft pop-up in Outlook, it shows a message saying my username might be incorrect. We don't have a dedicated IT support person, and the colleague who usually helps is just as confused. Despite having a software development background, I can't seem to resolve this issue after a month of trying. It's strange because the sign-in works temporarily but eventually kicks me out, and no login details seem to clear these prompts. Can someone guide me on how to fix this problem?
2 Answers
It sounds like Outlook isn't really asking for your mailbox password but rather a sign-in for Office itself. Even when you're using an on-prem Exchange setup, newer versions of Outlook still want to link to a Microsoft identity for licensing reasons. Here are a few things I’d suggest:
1. Close Outlook completely.
2. Go to Control Panel ➔ Credential Manager ➔ Windows Credentials and delete anything that relates to Microsoft Office or Outlook.
3. Open Word and go to your account settings to make sure Office is activated with the right Microsoft account.
4. Then restart Outlook and see if it helps!
Also, check if 'Modern Authentication' got enabled after a recent update, as it can disrupt older setups.
You might want to try a registry key change. There's a key you can add:
reg add HKEY_CURRENT_USERSoftwareMicrosoftOffice16.0OutlookAutoDiscover /t REG_DWORD /v ExcludeExplicitO365Endpoint /d 1
It might help prevent Outlook from reaching out to Office 365 servers for authentication. Just be cautious with registry changes, but it can solve the sign-in popup issue if you're not using 365.
I've tried this method, and while it works sometimes, there are instances when I still get the popup. It can vanish for weeks or just a few days before coming back. Still worth a shot!