Outlook will not open on my laptop

Check Microsoft’s service-health page first because Outlook and Microsoft 365 are experiencing widespread access problems today; if Outlook is listed as affected, use Outlook on the web temporarily and wait for Microsoft to resolve the incident rather than repairing the laptop.^1^ ^2^

If no outage is shown

Test classic Outlook without its add-ins:

1. Press Windows key + R.
2. Enter:

      outlook.exe /safe
   

3. Select OK, accept the default Outlook profile, and enter your password if requested.

If Outlook opens in safe mode, an add-in is probably preventing normal startup:

1. In Outlook, select File → Options → Add-ins.
2. At the bottom, choose COM Add-ins → Go.
3. Take a screenshot of the enabled add-ins.
4. Clear every checkbox and select OK. Disable them; do not select Remove.
5. Close and reopen Outlook normally.
6. Re-enable the add-ins individually, restarting Outlook each time, until the problem returns. Leave the responsible add-in disabled.^3^

If safe mode also fails

Try these in order:

1. Reset the navigation pane
   • Press Windows key + R.
   • Enter:

          outlook.exe /resetnavpane
     

   • Select OK.
2. Run Microsoft’s startup troubleshooter
   • Open Windows Get Help on the affected laptop.
   • Search for classic Outlook startup troubleshooter and follow its prompts.
   • This requires Windows 10 or later and applies to classic Outlook, not new Outlook.^4^
3. Create a new Outlook profile
   • Open Control Panel → Mail → Show Profiles → Add.
   • Create the profile and add the email account.
   • Hold Shift while starting Outlook, then select the new profile.
   • If it opens, the original Outlook profile is damaged. Do not remove the old profile until any locally stored data has been backed up.^3^
4. Repair Office
   • Open Settings → Apps → Installed apps.
   • Find Microsoft 365 or Microsoft Office.
   • Select Modify → Quick Repair.
   • If that fails, repeat and choose Online Repair.

If an error appears, record its complete wording. In particular, “Cannot start Microsoft Outlook,” “The set of folders cannot be opened,” and password or sign-in errors require different follow-up actions.

References

1. Microsoft outage: Live updates as mass issues reported with Outlook, 365
2. Microsoft service health status
3. I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook. Cannot open the Outlook Window” | Microsoft Support
4. Classic Outlook troubleshooters | Microsoft Support