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Black or Blank Login Screen Issue

Learn about the black or blank login screen issue affecting Outlook Desktop add-ins, including workarounds and Microsoft's official response to this known issue.

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What is the black login screen issue?

Some users experience a completely black or blank login screen when trying to authenticate with Microsoft 365 in Outlook Desktop. This affects the initial sign-in process for add-ins like SecureMailMerge, preventing users from completing authentication and accessing the add-in’s functionality.

Important: This is not a bug in SecureMailMerge but rather a known issue with Microsoft’s Office platform that affects all Outlook add-ins using authentication dialogs.

Which versions are affected?

This issue specifically affects:

  • Outlook Desktop (Classic Outlook) - Most commonly affected
  • Outlook on Windows - Particularly newer versions

This issue does NOT affect:

  • Outlook on the Web (outlook.com, office.com) - Works normally
  • New Outlook - Generally works normally
  • Outlook for Mac - Generally works normally

Microsoft’s official response

Microsoft has officially acknowledged this issue in their Office JavaScript API repository. According to their response from August 2024:

I have been able to repro[duce] this. Seems specific to Outlook as it works OK in other hosts. I have created an internal work item (ref: 10429519) to fix this. Unfortunately, we can’t comment on potential timeline for fixing it.

The issue has been added to Microsoft’s backlog with the status “in backlog - timeline for resolution is unknown.” Unfortunately, Microsoft has not announced an estimated time for a fix.

Common workarounds

While waiting for Microsoft to resolve this issue, try these workarounds in order:

1. Switch to Outlook on the Web

The most reliable solution is to use Outlook on the Web instead of the desktop application:

2. Close Outlook and clear browser cache

This resolves the issue for some users:

  1. Close Outlook completely (check Task Manager to ensure all Outlook processes are terminated)
  2. Clear your browser cache and cookies:
    • Chrome/Edge: Press Ctrl+Shift+Delete, select “All time”, check all boxes, click “Clear data”
    • Firefox: Press Ctrl+Shift+Delete, select “Everything”, check all boxes, click “Clear Now”
  3. Restart Outlook
  4. Try signing in to SecureMailMerge again

3. Try a different browser (if using web version)

If you’re already using Outlook on the Web and experiencing issues:

4. Update Office and Windows

Ensure you have the latest updates:

  • Windows Updates: Go to Settings > Update & Security > Windows Update
  • Office Updates: Open any Office app > File > Account > Update Options > Update Now

5. Try incognito/private browsing mode

If using Outlook on the Web:

  • Open your browser in incognito/private mode
  • Navigate to Outlook on the Web
  • Try using SecureMailMerge from there

What to do if workarounds don’t help

If none of the workarounds unfortunately, our support team cannot resolve this issue because:

  • This is a Microsoft platform issue, not a problem with SecureMailMerge
  • We have no control over how Outlook Desktop renders authentication dialogs
  • The issue affects all Outlook add-ins that use Microsoft 365 authentication
  • Only Microsoft can fix the underlying problem in their Office platform

We understand this issue is frustrating. Please know that we’re committed to providing the best mail merge experience possible, and we’re actively monitoring Microsoft’s progress on resolving this platform issue.