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Upgrade to Microsoft Troubleshoot Office 365 Sync and Login Issues 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. The folder may have been deleted or the server where the folder is stored may be unavailable. To access the filtering options faster, add them to your Quick Access Toolbar.
- The issues documented in this section have been reported after installing the recent updates listed below.
- This occurs because custom form script is now disabled by default.
- To access the filtering options faster, add them to your Quick Access Toolbar.
- You can also add the secondary connected accounts (Gmail, Yahoo, etc.) in Outlook.com as additional accounts in the Outlook profile.
Outlook Known issues in October 2020 updates

After installing the September Public Update, Outlook 2007 displays mixed languages in the user interface. If you are having problems with Outlook, Office 365 sync problems and login fixes there are a few things we can help with to get you back to sending and receiving your email. Find solutions to common problems or get help from a support agent. Please install the Windows 10 Fall Creators Update to fix this issue.
Outlook known issues in the January 2019 updates
Auto-archive, sending and receiving a very large attachment, or running Exchange connectivity diagnostic 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Most startup failures arise from minor configuration mismatches or outdated components.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

Stay updated, back up regularly, and enjoy uninterrupted productivity in your Outlook workspace. Online Repair reinstalls Outlook components while preserving your data, resolving DLL and registry mismatches that prevent startup. This process checks for structural issues and automatically fixes them. Occasionally, classic Outlook tries to run a process in the background.
Outlook issues after connecting Outlook to Outlook.com
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. 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.