If you have a large number of items in any single folder, you may experience performance issues during certain operations. For more information, see Outlook performance issues when there are too many items or folders in a cached mode .ost Repair Outlook Profile Online or .pst file. To create a user profile, you must first create a user account. To determine whether this problem is caused by a corrupted user profile, create a user profile to see whether the problem still occurs when you use the new profile. To keep up with new viruses as they're created, antivirus software vendors periodically provide updates that you can download from the Internet.

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

To learn more about how to send us feedback, please see How do I give feedback on Microsoft Office. To access the filtering options faster, add them to your Quick Access Toolbar. 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. Upgrade to Microsoft Edge to take advantage of the latest features, resolve Outlook not sending emails fast security updates, and technical support. If you use the cloud-based Microsoft 365 on a PC or Mac, the automated Support and Recovery Assistant tool can diagnose and fix many issues, including Microsoft Outlook not starting.

Outlook Known issues in September 2024 updates

• Right-click the folder, and then click Properties to check your permissions for the folder.
• After updating Office, you may experience a brief flashing window every hour, which triggers the OfficeBackgroundHandlerRegistration task to start running.
• Although add-ins can enhance your user experience, they can occasionally interfere or conflict with Outlook.
• These steps are provided in a specific order based on commonality and complexity.
• Outlook forwards meeting invitations to other attendees without anyone actually sending an update or forwarding an invite.
• This occurs because custom form script is now disabled by default.

The loading of unregistered MAPI services has been disabled by default to make Outlook more secure. To edit a shared calendar, go online to your own Outlook.com calendar, open Calendar for Windows 10, or use a mobile device. Maybe you've added a new program to your computer that doesn't get along with Outlook, or your system has a virus. Regardless of the specific cause, there are several key troubleshooting fixes to try that might help.

Outlook known issues in the June 2018 updates

This occurs because custom form script is now disabled by default. You must have at least three user accounts on the computer to complete these steps. You can automatically repair your Office program files to resolve such problems as Outlook freezing or not responding.

Outlook Known issues in November 2023 updates

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.

Outlook known issues in the December 2018 updates

If you've already clicked the Accept button in Outlook 2016, you won't be clear Outlook credentials manager able to re-accept the invitation from another Outlook application. The person who sent you the invitation will need to remove your permissions and then send a new invitation. For more information, see How to install the latest applicable updates for Microsoft Outlook (US English only). There is a new version of outlook that is web based, but still works like an app, and has less problems.



When you install Outlook, an Inbox repair tool (scanpst.exe) is also installed on your PC. The Inbox repair tool can resolve problems by scanning your Outlook data files, and repairing errors. To use the Inbox repair tool, exit Outlook, and then follow the steps in Repair Outlook Data Files (.pst and .ost). If your antivirus software includes integration with Outlook, you may experience performance issues. You can disable all Outlook integration within the antivirus software. Or, you can disable any antivirus software add-ins that are installed in Outlook.



If you have email messages in an email program, you must import your email messages and addresses to the new user profile before you delete the old profile. If everything is working correctly, you can now delete the old profile. In System Configuration, if you select a check box, the related service or startup program runs when you restart the computer. If the check box is cleared, the service or startup program doesn't run when you restart the computer.