Fix: Windows Defender application failed to initialize

Matthew Adams
by Matthew Adams
Windows & Software Expert
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Windows Defender is an anti-virus app included in Windows. However, some users have reported a Windows Defender error message along the lines of: “Windows Defender. Application failed to initialize:0x800106ba.” The error message might pop up during the Windows startup, and Windows Defender doesn’t open. So are you getting that software error? If so, here are a few potential fixes for it.

What to do if Windows Defender fails to initialize

Table of contents:

  1. Remove Third-Party Anti-Virus Software
  2. Turn Windows Defender off
  3. Check the Windows Defender Service Startup Configuration
  4. Re-register DLL Files for Windows Defender
  5. Install the latest updates
  6. Delete the most recent update
  7. Run the SFC scan
  8. Restart the Security Center Service
  9. Change your group policy

Fix – Windows Defender failed to initialize

Solution 1 – Remove Third-Party Anti-Virus Software

First, note that third-party anti-virus software usually undermines Windows Defender as a consequence of two anti-virus services running simultaneously. Some utilities such as McAfee and Norton even disable Windows Defender to free up system resources and prevent potential software errors. So if there are third-party anti-virus software running, that might be why you’re getting the 0x800106ba error. If you prefer to run Windows Defender, uninstall the other anti-virus programs with Advanced Uninstaller PRO, or other third-party software, to ensure there are no leftover registry entries.

  • First, press the Download Now button on this web page to save Advanced Uninstaller PRO’s setup wizard to Windows. Open the software’s installer to add the Advanced Uninstaller to Windows.
  • Now open the Advanced Uninstaller PRO window, and press the General Tools button.

  • Press the Uninstall Programs button to open the window below.

  • Select the anti-virus software you need to remove from there, and press the Uninstall button.
  • Then select the After uninstall, scan the disk and registry for program leftovers option.
  • Press Yes to uninstall the software.
  • Then click Next to scan for leftovers.
  • The software will then show you leftover items. Press the Select button to delete all leftover items.
  • Press the Next and Close buttons, close the software and restart the Windows platform.

Solution 2 – Turn Windows Defender off

  • If you only need to stop the 0x800106ba error message popping up, then switch Windows Defender off. You can do that by pressing the Cortana button and entering ‘Windows Defender’ in the search box.
  • Select Windows Defender settings to open further options.
  • Then you can switch the Real-time Protection option off.
  • In addition, switch off the Cloud-based Protection and Limited Periodic Scanning settings.

Solution 3 – Check the Windows Defender Service Startup Configuration

The Windows Defender Service startup configuration must be either Automatic or Automatic (Delayed Start). If it isn’t, that’s probably why Windows Defender isn’t initializing. You can configure the startup type for Windows Defender as follows.

  • Click the Cortana button on the Windows 10 taskbar and enter ‘services’ in the search box. Select Services to open the window directly below.

  • Now double-click Windows Defender Service to open the window in the snapshot below.

  • Select either Automatic or Automatic (Delayed Start) from the Startup type drop-down menu. The Automatic (Delayed Start) setting delays the Windows Defender startup until the other applications have loaded.
  • Click the Apply and OK buttons.
  • Then you can restart Windows.

Solution 4 – Re-register DLL Files for Windows Defender

Finally, reregistering Windows Defender DLL files can also fix the 0x800106ba error. First, open the Command Prompt by pressing the Win key + X and selecting Command Prompt (Admin). Then you should type all these files in the Command Prompt:

  • regsvr32 wuaueng.dll
  • regsvr32 wucltui.dll
  • regsvr32 softpub.dll
  • regsvr32 wintrust.dll
  • regsvr32 initpki.dll
  • regsvr32 wups.dll
  • regsvr32 wuweb.dll
  • regsvr32 atl.dll
  • regsvr32 mssip32.dll
  • Press Enter after entering each file. Restart Windows after re-registering the DLL files.

Solution 5 – Install the latest updates

As Windows Defender is a part of Windows 10, it receives updates through Windows Update. So, if the issue we’re dealing with is widespread, there’s a good chance Microsoft is working on the fix. To check if the patch is available, simply check for updates by going to Settings > Windows Update.

Solution 6 – Delete the most recent update

On the contrary, it could be a recent Windows Update that actually ‘breaks’ Windows Defender. If you suspect this may be the case, your best bet is to go and delete the most recent update. Here’s how to do that:

  1. Press Windows Key + I to open the Settings app.
  2. Once the Settings app opens, navigate to Update & security section.
  3. Go to Windows Update tab and click on Update history.
  4. Click on Uninstall updates.
  5. List of installed updates will now appear. Select the problematic update that you want to remove and click the Uninstall button.
  6. After removing the update, restart your PC.

Solution 7 – Run the SFC scan

In case Windows Defender files got corrupt, there’s a good chance you’ll see all sorts of errors, including this one. To make sure the files are repaired, we’re going to run the SFC scan. This is a command-line tool that scans the system for potential damaged system files, and repairs them (if possible).

Here’s how to run the SFC scan in Windows 10:

  1. Right-click the Start Menu button, and open Command Prompt (Admin).
  2. Enter the following line and press Enter: sfc/scannow
  3. Wait until the process is done (it may take a while).
  4. If the solution is found, it will automatically be applied.
  5. Now, close the Command Prompt and restart your computer.

Solution 8 – Restart the Security Center Service

Just like it’s the case with the Windows Defender service itself, the Security Center service is also crucial for running Windows Defender. In case this service doesn’t function properly, we’re going to restart in order to bring it back to working. Here’s what you need to do:

  1. Go to Search, type services, and open Services.msc.
  2. Scroll down and find the Security Center service.
  3. Right-click the Security Center service and click Restart.
  4. Wait for the system to restart the service.
  5. Restart your computer.

Solution 9 – Change your group policy

And finally, if none of the previous solutions resolved the problem, you can try with changing the group policy. Here’s what you need to do:

  1. Press Windows Key + R and enter gpedit.msc. Now press Enter or click OK.
    Windows Defender won't turn on after uninstalling Avast
  2. When Group Policy Editor opens, in the left pane navigate to Computer Configuration > Administrative Template > Windows Components > Windows Defender Antivirus. In the right pane, double click Turn off Windows Defender Antivirus.
    Windows Defender won't turn on Windows 10 Spybot
  3. Select Not Configured and click on Apply and OK to save changes.

Those are some of the best fixes for the 0x800106ba error code. If you still can’t get Windows Defender up and running after applying those fixes, check out this article.

Editor’s Note: This post was originally published in July 2016 and has been since completely revamped and updated for freshness, accuracy, and comprehensiveness.


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