This article describes how to troubleshoot Microsoft Outlook when it's used together with Microsoft 365 and:
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Outlook stops responding (hangs).
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Outlook crashes even though you aren't actively using it.
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Outlook crashes when you start it.
Try steps 1 through 3 in order until the issue is cleared. If you go through all of those steps and Outlook is still crashing or not responding, complete step 4 before contacting the Microsoft Community for further help.
Note: These steps are not applicable to new Outlook for Windows. Check to see if the new Outlook toggle is turned on or off. If it's on, please go to Troubleshooting Outlook issues.
1. Investigate possible issues caused by add-ins
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Exit Outlook.
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Press the Windows logo key
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Enter Outlook /safe, choose a profile if prompted, and then select OK.
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If Outlook doesn't crash or hang, continue by selecting File > Options > Add-Ins.
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At the bottom of the window, select COM Add-ins and then select Go.
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Select any active check boxes to clear them, and then select OK.
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Restart Outlook. If the issue doesn't recur, start adding the add-ins back one at a time.
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After adding each add-in, exit then re-open Outlook.
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If the issue doesn't recur, add the next add-in.
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Repeat until either all add-ins have been re-added, or the issue recurs.
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If the issue recurs, remove the last add-in to be added.
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2. Repair Office
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Type Control Panel in the search box at the bottom of the Windows screen.
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Select Uninstall a program from the Programs group.
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In the list of installed programs, right-click the entry for your Microsoft 365 installation and then select Change > Online Repair.
3. Create a new Outlook profile
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Type Control Panel in the search box at the bottom of the Windows screen.
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Select User Accounts > Mail.
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Select Show Profiles.
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Select the profile that you want to remove, and then select Remove.
Note: Removing a profile also removes any associated data files. If you're not sure whether the data files are backed up or stored on a server, do not remove the profile. Instead, skip to the next step.
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Select Add.
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Type a name for the new profile in the Profile Name box.
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Enter the user name and the primary SMTP address. Then select Next.
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You might see the message
Allow this website to configure <alias@domain> server settings?
Select the Don't ask me about this website again checkbox, and then select Allow. -
When prompted, enter your sign in credentials, and then select OK.
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When Setup is finished, select Finish.
4. Use the advanced diagnostic troubleshooter
Note: The classic Outlook advanced diagnostic troubleshooter is not applicable to new Outlook for Windows. Check to see if the new Outlook toggle is turned on or off. If it's on, please go to Troubleshooting Outlook issues.
Run the classic Outlook advanced diagnostic troubleshooter if you've tried all of the preceding steps and Outlook is still crashing or hanging. This step creates detailed information about your Outlook configuration and provides solutions for any known issues that are detected. It also gives you the option to upload your results to Microsoft so that a support engineer can review them.
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Select the button below to start the troubleshooter.
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Click Open if you get a pop-up window indicating This site is trying to open Get Help.
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Follow the steps in the Get Help window.
Important:
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You need to be on Windows 10 or higher to run the troubleshooter.
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You need to be on the same Windows PC as classic Outlook to run the troubleshooter.
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The troubleshooter won't work with new Outlook for Windows.
