When it comes to upgrading from an older version of the Windows operating system to Windows 10, Windows Defender takes the place of Microsoft Security Essentials, the previous built-in security tool. It is worth noting that a small percentage of all Windows 10 upgrades encounter issues. In some cases, users reported that Windows Defender had failed to start. The problem is usually accompanied by the Error Code 0x80070426.

If you are one of the few unlucky victims of this bug, do not despair yet because we’ve got you covered. In this post, we are going to share how to fix the Error 0x80070426 on Windows 10. Of course, we also want to free you from this curse forever. So, to prevent it from happening again, we will also discuss what causes the Windows Error Code 0x80070426.

What is the Error Code 0x80070426?

You may have noticed that when you upgraded to Windows 10, Windows Defender failed to replace Microsoft Security Essentials. Basically, the two antivirus programs are running on the new operating system.

Perhaps, you tried launching Windows Defender, but it failed to start. As such, you turned to Microsoft Security Essentials. However, when you opened it, you noticed that the Virus Protection and Spyware & Unwanted Software Protection features were disabled. So, you tried to switch them on. Unfortunately, a Microsoft Security Client dialog with the following error message showed up:

“An error has occurred in program initialization. If this problem continues, contact your System Administrator. Error Code: 0x80070426.”

To get rid of the Windows Defender Error 80070426, you need to uninstall Microsoft Security Essentials first. Once you’ve done that, you can follow our solutions below to get Windows Defender up and running.

Solution 1: Running an SFC Scan

It is likely that this error occurred during the upgrade process due to some problematic Windows system files in your computer. To determine if this is true, we recommend performing an SFC scan. Here are the steps:

  1. Go to your taskbar, then click the Search icon.
  2. Now, input “cmd” (no quotes).
  3. From the results, right-click Command Prompt, then select Run as Administrator.
  4. Once Command Prompt is up, run the command below:

dism.exe /online /cleanup-image /restorehealth

Note: If the error code appeared while you were upgrading, then instead of running the command above, you need to use your Windows installation media. After that, you must paste the text below on Command Prompt:

dism.exe /online /cleanup-image /restorehealth /source:[DRIVE]:\sources\sxs /limitaccess

Do not forget to replace [DRIVE] with the drive letter for your Windows installation media.

  1. Now, you need to wait for a couple of minutes for the process to complete. Once it is done, you can proceed to the next step.
  2. Type “sfc /scannow” (no quotes) in Command Prompt, then hit Enter.
  3. The scan process will take several minutes. Once it is complete, you can restart your computer.

Solution 2: Checking if there are Software Conflicts

As we’ve mentioned, the Error Code 80070426 occurs due to software conflicts. So, to ensure that no other program will interfere with Windows Defender, you must perform a clean boot. Doing so will allow you to launch your operating system with only the essential programs, services, and drivers. This process will help you determine if there are other items coming in conflict with Windows Defender. Once you’re ready, just follow the instructions below:

  1. Launch the Run dialog box by pressing Windows Key+R on your keyboard.
  2. Once the Run dialog box is up, input “msconfig” (no quotes), then hit Enter.
  3. Go to the Services tab, then make sure that the ‘Hide all Microsoft services’ option is selected.
  4. Now, click the Disable All button.
  5. Click OK.
  6. The next step is to go to the Startup tab. Once you are there, click the Open Task Manager link.
  7. Right-click all the startup items one by one, selecting Disable from the options.
  8. After disabling the startup items, exit Task Manager.
  9. Click OK and Restart.

After restarting your computer, check if the Error Code 0x80070426 is still there when you launch Windows Defender. If it isn’t, then you need to go back to the System Configuration window and enable a startup item. After that, restart your PC to see if the error is gone. Keep in mind that you need to perform this process for all the startup items until the Error Code 0x80070426 shows up again. Once you identify the culprit, you can disable it or remove it completely from your computer.

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Pro Tip: If you want optimum protection for your PC without the hassle of dealing with the Error Code 0x80070426, we suggest that you install Auslogics Anti-Malware. This software program can detect malicious items and threats no matter how discreetly they run in the background. Moreover, it can catch viruses and malware that Windows Defender may miss. As a certified Microsoft Silver Application Developer, Auslogics made sure that this tool will not conflict with your main antivirus.

Solution 3: Running the Windows Update Troubleshooter

As we’ve mentioned, the issue usually occurs because of problems during the upgrade process. So, to get rid of the Windows Defender Error 0x80070426, it is best that you run the built-in troubleshooter for updates. To do that, you need to follow the steps below:

  1. On your keyboard, press Windows Key+I. Doing so will launch the Settings app.
  2. Once the Settings app is open, click Update & Security.
  3. Now, go to the left-pane menu, then select Troubleshoot.
  4. Go to the right pane, then click Windows Update.
  5. Click the Run the Troubleshooter button.
  6. Follow the instructions on the troubleshooter to resolve the update issues.

Solution 4: Resetting the Windows Update Components

It is possible that some components of the updates were corrupted, prompting the Error 0x80070426 to appear. To resolve this problem, you simply need to reset all the services, folders, and files associated with Windows Update. Here are the instructions:

  1. You need to run Command Prompt as an administrator. To do that, you can press Windows Key+S on your keyboard, then type “cmd” (no quotes).
  2. Right-click Command Prompt from the results, then select Run as Administrator.
  3. Once Command Prompt is up, paste the lines below. Remember to input them one by one, pressing Enter on your keyboard after every command line.

net stop bits

net stop wuauserv

net stop appidsvc

net stop cryptsvc

  1. Run the commands below, pressing Enter on your keyboard after every line:

ren %systemroot%\softwaredistribution softwaredistribution.old

ren %systemroot%\system32\catroot2 catroot2.old

  1. You need to restart the services you disabled. So, you must type the commands below, pressing Enter on your keyboard after every line.

net start bits

net start wuauserv

net start appidsvc

net start cryptsvc

  1. Try installing the updates again, then check if you can launch Windows Defender without any issues.

Solution 5: Setting the Windows Update Services to Start Automatically

It is possible that the Windows Update services were not configured to start automatically, causing issues during the upgrade process. To fix this, you just have to follow the instructions below:

  1. Right-click the Windows icon on your taskbar.
  2. Select Command Prompt (Admin) or Windows PowerShell (Admin) from the list.
  3. Once Command Prompt or Windows PowerShell is up, run these commands:

SC config bits start= auto

SC config cryptsvc start= auto

SC config trustedinstaller start= auto

SC config wuauserv start= auto

Note: Remember to press Enter on your keyboard after every line.

  1. Exit Command Prompt or Windows PowerShell, then restart your computer.

Solution 6: Updating Your Device Drivers

There can be conflicts during the upgrade process if you’re using the wrong or outdated device drivers. So, you need to ensure that there are no issues with your drivers in order to get rid of the Error 0x80070426 on Windows 10. The best way to do this is to use Auslogics Driver Updater. After your installing this tool, it will automatically recognize your processor type and operating system version. All you need to do is click a button, and the program will locate, download, and install the latest compatible drivers for your computer.

Pro Tip: To ensure that your PC will perform smoothly after the upgrade, we encourage you to install Auslogics BoostSpeed as well. The powerful cleaning module of this software will effectively sweep out all types of junk in your PC and other items that may affect its performance. After using this tool, you can expect most operations and processes to go at a faster pace.

Can you think of other methods for resolving the Error 0x80070426?

Join the discussion below and share your thoughts!