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

• Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
• You might need to set Windows Update to automatically download and install recommended 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.
• To access the calendar shared with your Microsoft 365 for business account, you'll need to accept the invitation from Outlook on the web, iOS, or Android.
• Most startup failures arise from minor configuration mismatches or outdated components.
• We've run into some issues with the 'New' Outlook this week after 6+ months of usage that other may run into.
• By the end, you’ll know exactly how to restore your Outlook and prevent future errors.

I saw a reply to an issue similar to mine that mentioned going to the Registry Editor and followed Outlook Stuck on Synchronizing Folders 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.

Outlook known issues in the June 2017 security updates

This occurs because custom form script is now disabled by default. For persistent issues, use FixTechGuide’s automated tools to perform deep diagnostics and security checks. Stay updated, back up regularly, and enjoy uninterrupted productivity in your Outlook workspace. Online Repair reinstalls Outlook repair PST file without data loss components while preserving your data, resolving DLL and registry mismatches that prevent startup. This process checks for structural issues and automatically fixes them.



To edit a shared calendar, go online to your own Outlook.com calendar, open Calendar for Windows 10, or use a mobile device. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. You can start Outlook in safe mode, disable your add-ins, and then try to open Outlook normally. To access the filtering options faster, add them to your Quick Access Toolbar. You may notice that All, Unread , Mentioned and other sort and filtering options, such as By date, and Newest are missing in Outlook above your email list.



If you're using Outlook 2010, Outlook 2013 or Outlook 2016, uninstall and rebuild Outlook data file quickly re-install iCloud to resolve this issue.