Windows Defender is a crucial component of Windows security, but sometimes it encounters errors that prevent it from functioning properly. One such error is 0x800b0100, which typically appears with the message “An error has occurred in the program during initialization.” This error can leave your system vulnerable, so it’s important to address it promptly.
Check Windows Defender Services
The first step in resolving this error is to ensure that Windows Defender services are running correctly.
Step 1: Press Windows key + R to open the Run dialog, type services.msc, and press Enter.
Step 2: Locate “Windows Defender Antivirus Service” in the list.
Step 3: Double-click on the service and set the Startup type to “Automatic” if it isn’t already.
Step 4: If the service is not running, click the “Start” button.
Step 5: Repeat these steps for “Windows Defender Firewall” and “Windows Defender Advanced Threat Protection Service” if they are present.
After adjusting these services, restart your computer and check if the error persists.
Run System File Checker (SFC)
Corrupted system files can cause various errors, including issues with Windows Defender. The System File Checker tool can help identify and repair these files.
Step 1: Open Command Prompt as an administrator by right-clicking the Start button and selecting “Windows Terminal (Admin)”.
Step 2: Type the following command and press Enter:
sfc /scannow
Step 3: Wait for the process to complete. It may take several minutes.
Step 4: Restart your computer after the scan finishes.
Use DISM Tool
If SFC doesn’t resolve the issue, the Deployment Image Servicing and Management (DISM) tool can repair Windows image corruption.
Step 1: Open Command Prompt as an administrator.
Step 2: Run the following command:
DISM /Online /Cleanup-Image /RestoreHealth
Step 3: This process may take 20 minutes or more. Once completed, restart your computer.
Update Windows
Outdated Windows components can cause conflicts with Windows Defender. Ensuring your system is up-to-date can often resolve these issues.
Step 1: Open Settings by pressing Windows key + I.
Step 2: Navigate to “Windows Update” and click “Check for updates”.
Step 3: Install any available updates and restart your computer when prompted.
Perform a Clean Boot
A clean boot starts Windows with minimal drivers and startup programs, which can help identify if a third-party application is causing the error.
Step 1: Press Windows key + R, type msconfig, and press Enter.
Step 2: In the System Configuration window, go to the “Services” tab.
Step 3: Check “Hide all Microsoft services” and click “Disable all”.
Step 4: Go to the “Startup” tab and click “Open Task Manager”.
Step 5: Disable all startup items in Task Manager.
Step 6: Close Task Manager, click “OK” in System Configuration, and restart your computer.
If Windows Defender works correctly after a clean boot, gradually re-enable services and startup items to identify the conflicting application.
Reinstall Windows Defender
If all else fails, reinstalling Windows Defender might be necessary. This process involves using PowerShell to remove and reinstall the Windows Defender feature.
Step 1: Open PowerShell as an administrator.
Step 2: Run the following command to uninstall Windows Defender:
Uninstall-WindowsFeature -Name Windows-Defender
Step 3: Restart your computer.
Step 4: After restarting, open PowerShell as an administrator again and run:
Install-WindowsFeature -Name Windows-Defender
Step 5: Restart your computer once more.
Resolving the Windows Defender Error 0x800b0100 is crucial for maintaining your system’s security. If these methods don’t work, consider seeking help from Microsoft Support or a professional technician, as there might be deeper system issues at play.