After updating Office, you may experience a brief flashing window every hour, which triggers the OfficeBackgroundHandlerRegistration task to start running. For more information about when builds are available for their respective channels, go to Update history for Microsoft 365. We're investigating the issue and will update this page when a fix is available. MAPI does not validate that a provider's DLL that it is requested to load is registered correctly in MapiSVC.inf or even that it comes from the local machine. This can be exploited by creating a file together with an OLE object in such a way to cause MAPI to load a DLL from a network share when the OLE object is activated.

My Outlook 365 won't open after a Windows update yesterday.

Occasionally, classic Outlook tries to run a process in the background. Auto-archive, sending and receiving a very large attachment, or running some of the other mailbox tools can all be done in the background. Check the status bar at the bottom of the screen to see if another process is running. If so, wait a short time (usually two or three minutes) to see if Outlook starts working again. If you can't choose any of the menu options, type inside an email message, calendar event, or contact, Outlook may have frozen. There are three steps you can take to try to get Outlook working again.

Outlook Known issues in June 2022 updates

The issues documented in this section have been reported after installing the recent updates listed below. We're investigating the issues and will update this page when a fix is available. In the meantime, please use the workarounds suggested for each issue. If you manually type in the secondary connected account email address in the "From" field, the email is sent as "On behalf of" your primary Outlook.com account.

Outlook Known Issues in June 2021 updates

The loading of unregistered MAPI services has been disabled by default to make Outlook more secure. Currently, you can't use Outlook on Windows to edit calendars that are shared with your Outlook.com account, even if you've reconnected your Outlook.com account to Outlook. We're working to make it possible to edit shared calendars in Outlook 2016 for Windows. We've run into some issues with the 'New' Outlook this week after 6+ months of usage that other may run into.

Some Web-based Outlook add-ins don't work in when using on premise Exchange 2013

• When the Outlook app opens, I can see the 'Try the new Outlook' toggle.
• After updating Office, you may experience a brief flashing window every hour, which triggers the OfficeBackgroundHandlerRegistration task to start running.
• This command deletes the custom folder views, restoring default configurations.
• To edit a shared calendar, go online to your own Outlook.com calendar, open Calendar for Windows 10, or use a mobile device.
• I am opening the "classic" Outlook app on my computer because the one labeled new seems to not actually be a functioning app (no icon, nothing happens when I click on it).
• If your Microsoft Outlook won’t open after a recent Windows update, you’re not alone.

My computer (running Windows 11 Pro) forced an update about two weeks ago. Since the update, my Outlook will not return to "new" Outlook, it deleted my email signature, and is incredibly delayed in getting messages. I am opening the "classic" Outlook app on my computer because the one labeled new seems to not actually be a functioning app (no icon, nothing happens when I click on it). When the Outlook app opens, I can see the 'Try diagnose Office activation conflicts the new Outlook' toggle. The toggle just turns back off and the app does nothing different.



It’s harmless and resolves 30% of stuck startup issues according to Microsoft community reports. Until you can install the Windows Update fix release, you can FixTechGuide Outlook repair tutorial set a registry key that will cause Outlook to stop using the local Windows Search service. When this registry key is set, Outlook will use its own built-in search engine. The built-in search will display the message below to indicate it is not using the Windows Search service.



Many users encounter startup freezes, profile loading loops, and crashes following major Windows patches or Office updates. Fortunately, most of these errors stem from configuration conflicts, corrupted data files, or outdated components that can be fixed with a few targeted steps. If your Outlook suddenly stopped opening after a Windows update, don’t panic.



This ensures Outlook and Windows run the same DLL versions and registry references. Third-party add-ins are among the most common culprits for guide to Office 365 sign-in errors Outlook not opening properly. Safe Mode allows you to start Outlook with all extensions temporarily disabled.