Oulook Classic Frozen Again

Gail Martin 20 Reputation points
2026-01-29T11:55:14.14+00:00

After uninstalling the Windows update causing the problem ten days ago, per the directions in this formm, and regaining full access to Outlook last week, it is exhibiting the some of the same problems once again this morning (initially apparent as freezing; now won't open at all). Closing it with Task Manager and restarting the computer were not effective. What happened overnight?

Outlook | Windows | Classic Outlook for Windows | For home
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Answer accepted by question author
Chloe-L 13,710 Reputation points Microsoft External Staff Moderator
2026-01-29T19:14:01.3066667+00:00

Dear Gail Martin,

Thank you for posting to the Microsoft Q&A.

I understand how frustrating it is to have your workflow disrupted a second time, especially after you had already successfully regained access by rolling back the previous update. What likely happened overnight is that Windows performed an automatic update cycle. If your "Pause Updates" period expired, the system may have re-applied the problematic configuration. However, we now have a permanent solution that replaces the need for uninstalls.

To provide the most accurate solution, could you please confirm which version of Windows you are currently using? If you see KB5074109 listed in your update history again, it confirms why the freezing has returned.

The good news is that the engineering team released a permanent fix for this behavior on January 24, 2026. This new update, KB5078127, is designed to resolve the freezing and sync issues once and for all.

Please follow these steps to install the patch:

  1. Open Windows Settings.
  2. Go to Windows Update.
  3. Click Check for updates.
  4. Ensure you download and install Security Update KB5078127.
  5. Restart your computer once the installation is complete.

Updating to this version should resolve the sync issues and prevent Outlook from hanging during startup. If you continue to see prompts after checking these settings, please do not hesitate to let me know.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  1. AI answer

    2026-01-29T11:55:53.17+00:00

    It sounds like you're experiencing recurring issues with Outlook freezing or not opening at all. This can happen for several reasons, including:

    1. Outlook is in use by another process: Sometimes, other applications or processes can interfere with Outlook.
    2. Corrupted Outlook data files: If your Outlook data files are damaged, this can lead to freezing or failure to open.
    3. Conflicting add-ins: Previously installed add-ins may still be causing issues, even after uninstalling updates.
    4. Antivirus conflicts: Outdated or conflicting antivirus software can affect Outlook's performance.
    5. Large mailboxes: If your mailboxes are too large, this may also lead to performance issues.

    To troubleshoot, consider the following steps:

    • Run the Classic Outlook Advanced Diagnostics troubleshooter to identify potential issues automatically.
    • Check if your antivirus software is up-to-date and not conflicting with Outlook.
    • Repair your Outlook data files using the Inbox repair tool (scanpst.exe).
    • If the issue persists, you may want to perform a clean boot to eliminate any startup items or services that could be causing the conflict.

    If you continue to experience problems, it may be worth reinstalling Outlook or checking for any additional updates that may resolve these issues.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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