MS 365 apps not opening

Record the exact filename, path, and publisher shown in the Smart App Control notification, then update and repair the blocked component before considering disabling Smart App Control.

1. Identify what Smart App Control blocked

Before changing the security setting, reopen Word once and note or photograph:

• Blocked filename
• Full file path
• Publisher
• Any certificate or signature information displayed

Smart App Control checks the file being launched and blocks files considered malicious, unwanted, unsigned, or invalidly signed. It might therefore be blocking an Office executable, an add-in, or another component loaded with Office—not necessarily Word itself. Smart App Control applies to Windows 11, and there is no supported per-file exception or “Allow” list.^1^

• If the notification identifies a third-party add-in or utility, update, remove, or reinstall that component rather than disabling protection globally.
• If it identifies Word, Excel, PowerPoint, or another Microsoft Office file, continue below.

2. Update Windows and Microsoft Defender

Install all available Windows and Microsoft Defender updates, restart Windows, and test the Office apps again. Microsoft recommends having the latest Windows and Defender updates for Smart App Control.^2^

3. Repair Microsoft 365

If Microsoft Office files are still being blocked:

1. Right-click Start and select Installed apps.
2. Find Microsoft 365.
3. Select the three-dot menu → Modify.
4. For the usual Click-to-Run installation, select Online Repair → Repair.
5. For an MSI-based installation, select Repair → Continue.
6. Complete the repair, restart if prompted, and test Word, Excel, and PowerPoint.

Online Repair repairs the entire Office suite and is more comprehensive than Quick Repair.^3^

4. Disable Smart App Control only as a last resort

If current, repaired Microsoft 365 files are still blocked and the apps are urgently needed:

1. Open Windows Security from Start.
2. Select App & browser control.
3. Select Smart App Control settings.
4. Change Smart App Control to Off.
5. Test the Microsoft 365 apps.

This lowers protection for all applications; Smart App Control cannot allow only Word, Excel, or PowerPoint. Recent Windows updates may permit it to be enabled again from Windows Security when that option is available for the device, but Evaluation mode cannot be restored after manually switching modes without resetting or reinstalling Windows.^1^^2^

If genuine Microsoft Office files remain blocked after updates and Online Repair, contact Microsoft Support and provide the blocked filename, full path, publisher, and a screenshot of the notification.

References

1. Smart App Control Frequently Asked Questions | Microsoft Support
2. App & browser control in the Windows Security App | Microsoft Support
3. [Windows 11](https://support.microsoft.com/office/lifecycle/repair-an-office-application)