Microsoft Outlook 365 get hung up and becomes unresponsive

Question

Microsoft 365 Outlook is unresponsive. I've tried everything in the Microsoft repair instructions and still issues.

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Moved from: Microsoft 365 and Office | Other

Answer 1

Hi Gary Short

Just checking in — have you had a chance to review my message above? I’d love to hear from you.

Best regards

Answer 2

Dear Gary Short

Thank you for reaching out to the Microsoft Q&A forum. Please confirm which Outlook you’re using (Classic Outlook for Windows or the New Outlook) and the exact version/build (open Outlook > File > Office Account > About Outlook and share the Version/Build or a screenshot). When the freeze occurs, do you see any error pop‑ups or codes? If possible, attach a screenshot of the “Not Responding” state or any error dialog so I can pinpoint the cause. 

Look forward to hearing from you.  

Answer 3

Follow these targeted steps that go beyond the basic repair instructions already tried:

1. Start Outlook in Safe Mode and disable add-ins
   Add-ins are a common cause of hanging and “Not Responding”.
   • Close Outlook.
   • Press Windows logo key + R.
   • Type Outlook /safe and select OK.
   • If Outlook runs without hanging, go to File > Options > Add-Ins.
   • At the bottom, select COM Add-ins and then Go.
   • Clear all check boxes to disable all add-ins, select OK, then restart Outlook normally.
   • If Outlook is now stable, re-enable add-ins one at a time, restarting Outlook after each, until the problematic add-in is found and left disabled.
2. Repair Office with Online Repair
   If only a Quick/Local repair was done, run a full Online Repair:
   • Open Control Panel → Uninstall a program.
   • Right-click the Microsoft 365/Office installation → Change → Online Repair.
   • Complete the repair and test Outlook again.
3. Repair Outlook data files (.pst/.ost)
   Corrupted data files can cause freezing and non-responsiveness.
   • Close Outlook.
   • Use the Inbox Repair Tool (SCANSPST.EXE) as described in Repair Outlook Data Files (.pst and .ost).
   • Run the scan on each .pst/.ost file used in the profile until no errors are reported.
   • Restart Outlook and test.
4. Create a new Outlook profile
   A corrupted mail profile is a frequent cause of hangs and crashes.
   • Open Control Panel → Mail → Show Profiles.
   • Select the existing profile and choose Remove only if data is confirmed backed up or stored on the server. Otherwise, leave it and just add a new one.
   • Select Add, enter a Profile Name, then configure the account (user name and primary SMTP address).
   • Complete setup and test Outlook with the new profile.
   • If the new profile works, keep using it and optionally remove the old one later.
5. Run the Outlook diagnostics
   If Outlook still hangs or is unresponsive after the steps above:
   • Run the Classic Outlook Connectivity troubleshooter and, if needed, the Microsoft Support and Recovery Assistant as described in the crash/connection troubleshooting articles. These tools automatically check for common causes (add-ins, profile, data files, configuration) and propose fixes.
   • If Outlook continues to crash or hang, run the Classic Outlook Advanced Diagnostics troubleshooter to generate a detailed configuration report and suggested resolutions.
6. Ensure Windows and Office are fully updated
   • Install the latest Windows Update and Office updates as described in the update guidance. Many Outlook hanging issues are resolved by current patches.

If all of the above have been completed and Outlook remains unresponsive, use the Advanced Diagnostics report to open a support case so a support engineer can review the collected data.

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References:

• How to troubleshoot issues that cause Outlook to crash or stop responding when used with Microsoft 365
• Outlook crashes or stops responding when used with Office 365
• Outlook not responding error or Outlook freezes when you open a file or send mail
• Outlook not responding, stuck at "Processing," stopped working, or freezes
• Fix Outlook connection problems for Microsoft 365 account