MS Office (word, Excel ) not starting.

Run an Online Repair of Microsoft 365/Office because both Word and Excel show the same startup error; this repairs the complete Office installation rather than only the affected application.

Run Online Repair

1. Close all Office applications.
2. Open the repair settings:
   • Windows 11: Right-click Start → Installed apps.
   • Windows 10: Right-click Start → Apps and Features.
3. Find Microsoft 365 or Microsoft Office.
4. Select the three dots (or select the product) → Modify.
5. Choose the option presented for your installation:
   • Click-to-Run: Select Online Repair → Repair.
   • MSI-based Office: Select Repair → Continue.
6. Allow the process to finish, then restart Windows.
7. Open Word and Excel and confirm that each reaches a blank document or workbook without displaying the error.

Online Repair is preferable here because it performs a more complete repair than Quick Repair and repairs the entire Office suite.^1^ A matching case affecting multiple Office applications was also resolved by performing the full Online Repair rather than relying on the error dialog’s Repair Now button.^2^

If Online Repair does not resolve it

Test each application in Office Safe Mode:

1. Press Windows key + R.
2. Enter the following command for Word:

      winword /safe
   

3. Repeat for Excel:

      excel /safe
   

The space before /safe is required. If an application starts, its title bar should show Safe Mode.^3^

If Word or Excel works in Safe Mode:

1. Select File → Options → Add-ins.
2. At the bottom, choose COM Add-ins from Manage, then select Go.
3. Clear one add-in at a time and restart the application normally.
4. When normal startup succeeds, leave the problematic add-in disabled or obtain an updated version from its publisher.^3^

If neither application starts in Safe Mode after Online Repair, the documented next path is to uninstall and reinstall Office. Before doing so, confirm that the Office licence or Microsoft 365 subscription is associated with the Microsoft account needed for reinstallation.^2^

References

1. [Windows 11](https://support.microsoft.com/office/lifecycle/repair-an-office-application)
2. All microsoft office applications Excel, Word, Outlook, Etc. open with error and cannot be used - Microsoft Q&A
3. I get a "stopped working" error when I start Office applications on my PC | Microsoft Support