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 only other change to the Exchange Server was a certificate update for IIS. This is a standard DigiCert wildcard cert that we have replaced every year with no issues. If you can't open Outlook, or Outlook disappears or crashes, one of your add-ins may be to blame or you may need to update Outlook. Right-click the folder, and then click Properties to check your permissions for the folder. See the folder owner or your administrator to change your permissions.

Outlook Known Issues in June 2021 updates

You might need to set Windows Update to automatically download and install recommended updates. Installing any important, recommended, and optional updates can often correct problems by replacing out-of-date files and fixing vulnerabilities. To install the latest Windows and Office updates, click the link below. Please install the latest updates on your phone to resolve the issue.

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

• Online Repair reinstalls Outlook components while preserving your data, resolving DLL and registry mismatches that prevent startup.
• Outlook 2016 freezes when you try to preview an Excel file that's attached to an email.
• Stay updated, back up regularly, and enjoy uninterrupted productivity in your Outlook workspace.
• If you can't open Outlook, or Outlook disappears or crashes, one of your add-ins may be to blame or you may need to update Outlook.
• You can also add the secondary connected accounts (Gmail, Yahoo, etc.) in Outlook.com as additional accounts in the Outlook profile.
• Installing any important, recommended, and optional updates can often correct problems by replacing out-of-date files and fixing vulnerabilities.
• We're investigating the issue and will update this page when a fix is available.

I saw a reply to an issue similar to mine that mentioned going to the Registry Editor and followed reset cached Exchange mode instructions outlined in that message but nothing changed. By the end, you’ll know exactly how to restore your Outlook and prevent future errors. If your Microsoft Outlook won’t open after a recent Windows update, you’re not alone.



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 Outlook OST Vs PST Repair 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.

Repair Outlook OST File Not Working in Office 365 – Complete Fix (

This ensures Outlook and Windows run the same DLL versions and registry references. Third-party add-ins are among the most common culprits for Fix Outlook and Office 365 Errors 2025 Outlook not opening properly. Safe Mode allows you to start Outlook with all extensions temporarily disabled.