It is troubling to see an error with your Windows Defender since the software helps in protecting your computer. A problem with your computer’s built-in protection will expose you to a possible threats.
If you encounter the error code 0x800b0100 on Windows Defender running in Windows 10, there’s no need to worry. While the error blocks your Windows Defender from operating, there are still ways on how you can fix it.
Turn your Windows Defender back on full function again in no time.
Check out the solutions below to know how to solve the issue.
Fixing Error Code 0x800b0100 on Windows Defender

Solution #1 – Set Your Windows Defender Startup to Automatic
- Launch the Run dialog box by pressing Windows key + R.
- Type services.msc and press Enter.
- Look for Windows Defender Antivirus Service.
- Double click on the name to open a new window.
- Under the General tab, look for the Startup type.
- Set it to Automatic.
- Click Apply at the bottom and click OK.
Solution #2 – Run a SFC
- Open the Command Prompt with Administrative privileges by pressing Windows key + X.
- Type sfc /scannow and press Enter.
- Wait for the scan to finish.
- Once done, restart your computer.
Solution #3 – Perform a DISM
- Open the Command Prompt (Admin) by pressing Windows key + X.
- Type DISM /Online /Cleanup-Image /RestoreHealth and press enter.
- Wait for the scan to finish before restarting your computer.
Solution #4 – Perform a Clean Boot
Here is how to perform a clean boot on Windows 10.
- Press Windows key + R to open the run dialog box.
- Type msconfig and press Enter.
- Click the Services tab.
- Look for the options that say Hide All Microsoft Services and click the boxes.
- Next, click Disable all.
- Along the tabs, click Startup.
- Choose Task Manager.
- Right-click on a process and click Disable. Do the same to all processes.
- Click OK and restart your computer.
An error with your Windows Defender can leave you defenceless but following the solutions above will help you fix the. Follow the methods one at a time and see which one is more effective for you.
Did the solutions help you? Let us know in the comments below.