The most common reason is a broken Windows Security app package or damaged system files, while other causes include conflicts with third-party antivirus, Fast Startup getting in the way, or registry limits. Now that we’ve covered the possible causes on Windows 11, let’s go through the proven fixes other users used to restore normal Windows Security functionality.
1. Reset the Windows Security app package
A typical reason for this issue is corruption in the Windows Security app package (Microsoft.SecHealthUI). If this applies, resetting the package usually helps. To do this, open PowerShell with administrator rights and run a command that resets the Windows Security package. Many users confirmed this works.
2. Disable or uninstall 3rd-party antivirus
Some third-party antivirus suites (like Kaspersky) can block the native Windows Security app while they’re active. Turning off or removing the third-party AV can resolve the conflict. If you’re using a third-party suite, first disable its real-time protection and test Windows Security. If you want to be sure the AV isn’t involved—especially if it includes a firewall—uninstall the suite and remove any leftover files. Start with the simple step: turn off real-time protection. The exact steps vary by product, but you can usually do this from the antivirus icon in the taskbar. Disable real-time protection for a while, then check whether Windows Security opens. If you’re still having trouble, fully uninstall the security program and remove leftovers that might still cause the issue. If you choose this route, follow these instructions to thoroughly remove a third-party security suite and all leftover files.
3. Reset the Windows Security app
If Windows Security has corrupted cached data, the app might not open. Resetting the Windows Security app from Settings is a good first step. If you suspect this applies, open the Apps & Features page in Settings and trigger a full reset for Windows Security.
4. Enable Windows Security via Registry Editor
If you previously changed Windows Security’s default behavior, a Registry key might have disabled it. You can re-enable it by editing the DisableAntiSpyware value in Registry Editor. Be careful when changing the registry. Back it up first—incorrect changes can cause system issues.
5. Reinstall Windows Security
If you recently upgraded to Windows 11, parts of the Windows Security app may have been corrupted during the process. Reinstalling (re-registering) the component should fix it. This isn’t new—Windows 10 users reported similar issues after major updates. The fix is straightforward. Run a couple of commands to re-register built-in apps (including Windows Security) with fresh copies.
6. Run SFC and DISM scans
If you’re still stuck, you may be dealing with system file corruption that’s breaking Windows Security. Run SFC (System File Checker) and then DISM (Deployment Image Servicing and Management). These built-in tools fix common system file issues. SFC uses local files, while DISM pulls healthy files from Windows Update. Start with an SFC scan from an elevated CMD prompt. Do not interrupt the scan, even if it looks stuck. It will finish and show a result. After SFC completes, restart your computer. Then run a DISM scan. Make sure you have a stable Internet connection before running DISM. After DISM completes, restart your PC and test Windows Security again.
7. Repair install or clean install
If none of the methods above worked, your best option is to replace all affected system files with healthy ones. You can either perform a repair install (in-place upgrade) or a clean install. If possible, we recommend a repair install first:
Repair install – Reinstalls Windows while keeping your personal files, apps, games, and settings. Only system files are replaced.Clean install – Reinstalls Windows from scratch. This can fix deeper issues but will erase all personal data on the OS drive. Back up your files first.
