Are you seeing Windows Defender Error 0x800106ba when trying to open or run a security scan on your Windows 10 or Windows 11 PC? This error can be frustrating because it may prevent Microsoft Defender Antivirus from starting correctly, leaving you unsure whether your computer is adequately protected.
This error is commonly associated with problems starting the antivirus service, damaged system files, incorrect service settings, or conflicts with third-party antivirus software. In some cases, Windows security components may also need repairing or updating.
In this guide, you’ll learn how to fix Windows Defender Error 0x800106ba on Windows 10 and Windows 11.
Fix Windows Defender Error 0x800106ba
To fix Windows Defender Error 0x800106ba, try these steps in order:
- Restart your computer and check whether Microsoft Defender starts normally.
- Open the Services app and inspect the Microsoft Defender Antivirus Service.
- Run the DISM and SFC commands in an administrator terminal.
- Check whether another antivirus program is installed and active.
- Install pending Windows updates and restart your PC.
- Review Windows Security settings and repair or reset the relevant app if the option is available.
Let’s explore the steps in detail!
1: Restart Your Computer
Before changing any system settings, restart your computer. Sometimes, Windows Defender fails to start because of a temporary service issue, an incomplete update, or another process that did not shut down correctly.
Save your open documents and close your applications. Open the Start menu, select the Power option, and choose Restart. Wait for Windows to shut down and load again.
After signing in, open Windows Security by searching for it in the Start menu. Select Virus & threat protection and check whether Microsoft Defender is working normally. If you can start a scan without seeing the error, the issue may have been temporary.
Follow this path: Start > Power > Restart > Windows Security > Virus & threat protection.
If Error 0x800106ba appears again, continue to the next step instead of repeatedly restarting your computer.
2: Check the Microsoft Defender Antivirus Service
Microsoft Defender relies on Windows services to provide real-time protection and run security scans. If the relevant service is stopped, disabled, or unable to start, you may encounter an error.
Press Windows + R, type services.msc, and press Enter to open the Services window. Find Microsoft Defender Antivirus Service in the list. You can also look for other Defender-related services if the main service is unavailable.
Double-click the service to view its properties. Check its current status and startup configuration. On supported Windows versions, this service may be protected by Windows, and its startup settings may be controlled by the operating system or security policies.
The navigation path is Windows + R > services.msc > Microsoft Defender Antivirus Service > Properties.
If the service is stopped and Windows allows you to start it, select Start. If the controls are unavailable or you receive an access error, do not force changes through the Registry or third-party tools. The service may be managed by Windows, your organization, or another antivirus product.
Once you finish checking, reopen Windows Security and try a scan. If the service is already running or the error persists, proceed to the next method.
3: Repair Windows System Files Using DISM and SFC
Damaged or missing Windows system files can interfere with security services and cause unexpected errors. Windows provides two command-line tools, DISM and System File Checker (SFC), that can help repair these problems.
Right-click the Start button and select Terminal (Admin) on Windows 11 or Windows PowerShell (Admin) on Windows 10. If prompted by User Account Control, select Yes.
First, run this command and press Enter:
DISM /Online /Cleanup-Image /RestoreHealth
Allow the command to finish. DISM checks and repairs the Windows component store, which SFC can use to restore damaged system files. The process may take several minutes, and the progress percentage can sometimes appear to pause. Wait for it to complete.
Next, run:
sfc /scannow
Wait until the scan reaches 100 percent and displays its results. Windows may report that it found no integrity violations, repaired damaged files, or found files it could not repair.
Follow this path: Start (right-click) > Terminal (Admin) > DISM command > SFC command.
Restart your PC after the repairs, then open Windows Security and check whether the error has disappeared. If SFC cannot repair some files, you may need to investigate Windows Update or other system repair options.
4: Check for Conflicts With Third-Party Antivirus Software
Another antivirus program can affect Microsoft Defender’s availability. When a compatible third-party antivirus product is installed and registered with Windows Security, Microsoft Defender Antivirus may automatically switch to a passive or disabled state.
Open Settings > Apps > Installed apps in Windows 11. In Windows 10, open Settings > Apps > Apps & features. Review the list for security software such as Norton, McAfee, Avast, or another antivirus product.
If you intend to use Microsoft Defender as your primary antivirus, uninstall any unwanted third-party antivirus program using its official uninstaller or Windows Settings. Restart your PC and check Windows Security again.
The navigation path is Settings > Apps > Installed apps > Select the antivirus program > Uninstall.
Do not remove security software that your workplace requires, and avoid leaving your computer without active antivirus protection. If you want to keep your existing antivirus, check its status and consult its support documentation instead of forcing Microsoft Defender to run in an unsupported configuration.
5: Install Pending Windows Updates
An outdated Windows installation can contain security component problems that are addressed by later updates. Installing available updates is a straightforward way to make sure your system has current fixes.
On Windows 11, open Settings > Windows Update. On Windows 10, open Settings > Update & Security > Windows Update. Select Check for updates and allow Windows to search for available updates.
Install relevant security and quality updates, then restart your computer if prompted. If a separate Microsoft Defender security intelligence update is offered through Windows Update, install it as well.
Follow this path: Settings > Windows Update > Check for updates > Install available updates.
After updating, open Windows Security and check whether Virus & threat protection loads correctly. If Windows Update itself reports an error, resolve that problem before assuming Defender is still damaged.
6: Repair or Reset the Windows Security App
If Windows Security is not opening properly or displays an error when you access its settings, repairing the app may help. Keep in mind that the Windows Security interface and the Microsoft Defender Antivirus engine are related but separate components. Resetting the interface will not necessarily repair an underlying antivirus service problem.
Open Settings > Apps > Installed apps in Windows 11. Search for Windows Security, open its advanced options if available, and select Repair. This attempts to fix the app without removing its data.
If repairing does not help, you may see a Reset option. Resetting the app can restore its app settings, so try Repair first and use Reset only if necessary. The exact options vary by Windows version.
The navigation path is Settings > Apps > Installed apps > Windows Security > Advanced options > Repair.
If Windows Security does not appear in the app list or these options are unavailable, skip this method and continue troubleshooting. Do not download replacement security applications from unofficial websites.
7: Check Windows Security for Managed or Disabled Protection
If the error persists, determine whether Microsoft Defender is being managed by a work or school policy, another antivirus program, or a previous configuration change.
Open Windows Security > Virus & threat protection and look for information about your antivirus provider and protection status. If your device is managed by an organization, certain settings may be unavailable because an administrator controls them.
You can also open Windows Security and review the Manage providers option, if available, to see which antivirus provider Windows recognizes.
The navigation path is Windows Security > Virus & threat protection > Manage providers.
If another antivirus provider is active, Defender’s behavior may be expected. If no provider is active, or your personal PC reports that protection is unavailable, continue with the earlier repair steps and check for updates. On a managed computer, contact your IT administrator before changing security policies or service settings.
FAQs
1. What causes Windows Defender Error 0x800106ba?
This error may occur because of a problem starting the Microsoft Defender Antivirus service, corrupted system files, conflicting antivirus software, or Windows configuration issues. The exact cause depends on your computer.
2. Can I fix Error 0x800106ba without reinstalling Windows?
Yes. Start with a restart, check the Defender service, run DISM and SFC, review other antivirus software, and install Windows updates. These methods can resolve many common causes without reinstalling Windows.
3. Is Windows Defender available on Windows 10 and Windows 11?
Yes. Microsoft Defender Antivirus is included with supported Windows 10 and Windows 11 installations. Its availability and operating mode can depend on your Windows edition, organizational policies, and whether another antivirus product is active.
4. Should I manually enable the Microsoft Defender service?
Not necessarily. Windows may protect the service’s configuration or manage its startup automatically. Check its status first, and avoid forcing changes through the Registry or other unsupported methods.
5. Will resetting Windows Security delete my files?
Repairing or resetting the Windows Security app should not delete your personal documents, photos, or other files. However, resetting the app may reset its application settings, and it does not guarantee that the underlying antivirus problem will be resolved.
6. What if Windows Defender still does not work after these fixes?
Check whether another antivirus program is active, confirm that Windows is up to date, and review any available Defender-related error details. If the issue continues, you may need additional Windows repair steps or help from Microsoft support.
Final Words
Windows Defender Error 0x800106ba can prevent Microsoft Defender Antivirus from starting or operating correctly, but it does not automatically mean your computer is infected or that Windows needs to be reinstalled.
Start with the simplest solutions, including restarting your PC, checking the Defender service, and installing pending updates. If the error remains, use DISM and SFC to repair Windows system files, then investigate antivirus conflicts and Windows Security app problems.
Most importantly, make sure another trusted antivirus product is protecting your computer while you troubleshoot.
Avoid disabling security services or making unsupported Registry changes just to get past the error.