Outlook constantly not responding

Question

More than a week now, Outlook is unusable. Whenever I try to send it just shut down it would not let me do anything. Please helpppp

Answer 1

Hi Jason, 

Welcome to Microsoft Q&A Forum!  

Have a good day and I hope you're doing well! 

I understand how frustrating it is to have Outlook unusable for over a week, especially when it crashes right when you try to send emails. 

Based on the symptoms you described and the timeline, it appears you are likely experiencing a known issue caused by the Windows Update (KB5074109) released on January 13, 2026. 

Microsoft has confirmed that this update may cause Classic Outlook to freeze, become unresponsive, or force quit which matches your issue perfectly.  

Please note that this specific behavior primarily affects users with POP account profiles. 

First, please check if your computer recently installed the problematic update: 

1. Go to Settings > Windows Update. 
2. Select Update history. 
3. Look for KB5074109 in the list of installed updates. 

If you see that update listed, the good news is that Microsoft has released an official "Out-of-band" fix to resolve this crash. You need to install update KB5078127. 

You can find the detailed instructions and download the fix here:  January 24, 2026—KB5078127 (OS Builds 26200.7628 and 26100.7628) Out-of-band 

I hope this helps resolve the crashing issue. If the problem persists after applying the fix, please let me know, and provide a few more details about your setup so I can investigate further. 

If I’ve misunderstood anything or if something is unclear, please feel free to let me know.

Best regards. 

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Answer 2

If Outlook is constantly not responding, there are several steps you can take to troubleshoot the issue:

1. Check for External Content Issues: Prevent Outlook from downloading external content by going to File > Options > Trust Center > Automatic Download. Select the options to not download pictures or other content automatically in HTML emails and to warn before downloading content when editing, forwarding, or replying to emails.
2. Investigate Add-Ins: Sometimes add-ins can interfere with Outlook. Start Outlook in safe mode to see if the problem persists. You can do this by typing Outlook.exe /safe in the Run dialog. If Outlook works fine in safe mode, disable all add-ins and then re-enable them one at a time to identify the problematic one.
3. Check Mailbox Size: A large mailbox can cause performance issues. Ensure your mailbox is not too large and consider archiving old emails.
4. Repair Office Programs: You can automatically repair your Office installation. Exit any Office programs, go to Control Panel > Programs and Features, right-click on Microsoft Office, and select Repair.
5. Check Antivirus Software: Ensure your antivirus software is up-to-date and check if it conflicts with Outlook. You may need to disable any Outlook integration within your antivirus software to see if that resolves the issue.
6. Create a New User Profile: If the problem persists, consider creating a new user profile in Outlook. Go to Control Panel > Programs > User Accounts > Mail, select Show Profiles, and then add a new profile.

If these steps do not resolve the issue, further investigation may be necessary to identify any underlying problems.

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References:

• Outlook not responding error or Outlook freezes when you open a file or send mail