You might need to set Windows Update to automatically download and mailbox not updating on IMAP 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 Installing any important, recommended, and optional updates can often correct problems by replacing out-of-date files and fixing vulnerabilities.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.

• To learn more about how to send us feedback, please see How do I give feedback on Microsoft Office.
• 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.
• This solution prevents display rendering errors that occur after driver or DirectX updates.
• Third-party add-ins are among the most common culprits for Outlook not opening properly.
• If you're using Outlook 2010, Outlook 2013 or Outlook 2016, uninstall and re-install iCloud to resolve this issue.
• For more information about when builds are available for their respective channels, go to Update history for Microsoft 365.
• We're investigating the issues and will update this page when a fix is available.

Outlook Known issues in October 2020 updates

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 Exchange connectivity diagnostic the folder owner or your administrator to change your permissions. There is currently no option to revert to the prior behavior, but we would love to hear your feedback to help us with future designs.

Outlook known issues in the January 2019 updates

Auto-archive, sending and receiving a very large attachment, or running mailbox not updating on IMAP 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. 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.

Troubleshoot Outlook for Windows issues

Most startup failures arise from minor configuration mismatches or outdated components. Following the above steps—from safe mode diagnostics to repairing data files—will restore functionality in most cases. FixTechGuide’s free email diagnostic tools automate error detection by scanning your configuration files, registry entries, and mail protocols. The platform validates SMTP, IMAP, and POP3 settings against verified databases to identify version mismatches or broken profiles introduced after system updates.

Outlook Known issues in March 2025 updates

If you've already clicked the Accept button in Outlook 2016, you won't be 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. If you typically use an Outlook.com account for email, this issue can occur if there are multiple aliases on the account and the 3rd party email address is the primary alias.

Outlook issues after connecting Outlook to Outlook.com

Third-party add-ins are among the most common culprits for Outlook not opening properly. Safe Mode allows you to start Outlook with all extensions temporarily disabled. 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.