Fix: Essentials Error 0x80070426 in Windows 10

As of Windows 10, Microsoft Security Essentials is no longer available; it has been replaced by a program called “Windows Defender”. When you upgrade from a previous version of Windows to Windows 10, Windows Defender takes over and replaces Microsoft Security Essentials. However, in approximately 10% of all Windows 10 upgrades, something goes wrong and Windows Defender fails to replace Microsoft Security Essentials, resulting in the operating system having both Microsoft Security Essentials and Windows Defender installed.

In such instances, Windows Defender fails to start, implying that it does not provide any protection to the computer whatsoever. Even though Microsoft Security Essentials is always operational, its Spyware and Unwanted Software Protection, as well as Virus Protection, are both deactivated. When the user attempts to enable these disabled protection features, a Microsoft Security Client dialog appears, displaying the following error message:”.

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

Although error code 0x80070426 usually refers to a non-genuine copy of Windows, in this instance, the error is indicating that MSE is not functioning correctly. When error 0x80070426 occurs, it leaves your computer entirely vulnerable; both Windows Defender fails to start up and MSE ceases to work properly.

The solution to this problem is to simply uninstall Microsoft Security Essentials, allowing Windows Defender to do its job and protect your computer.

The following are all of the steps you need to follow in order to fix error 0x80070426.

Hold the Windows Key and press R. Type ‘taskmgr’ in the run dialog. Locate the Windows Defender Service (WinDefend), right-click on it, and choose ‘Stop’.


This should stop the service, but it will start automatically after the computer reboots. While it is stopped, you can uninstall Essentials. Normally in such cases, you cannot uninstall Microsoft Security Essentials because Windows Defender is programmed to block both the installation and uninstallation of Microsoft Security Essentials.

However, you should be able to uninstall Microsoft Security Essentials as though it were any other program now since the Windows Defender has been temporarily disabled.

To uninstall it, go to Control Panel -> Programs & Features -> Uninstall a Program, or hold the Windows Key and press R. Type “appwiz.cpl” and click OK, locate Microsoft Essentials, and uninstall it. Then, restart your computer.

After the reboot and removal of Essentials, proceed to ‘Settings -> Update & Security’. Choose ‘Windows Defender’ and ensure that Real-time protection is switched on.

Now go back to Task Manager -> Services tab and make sure that the Defender service is running.


Kevin Arrows

Kevin Arrows is a highly experienced and knowledgeable technology specialist with over a decade of industry experience. He holds a Microsoft Certified Technology Specialist (MCTS) certification and has a deep passion for staying up-to-date on the latest tech developments. Kevin has written extensively on a wide range of tech-related topics, showcasing his expertise and knowledge in areas such as software development, cybersecurity, and cloud computing. His contributions to the tech field have been widely recognized and respected by his peers, and he is highly regarded for his ability to explain complex technical concepts in a clear and concise manner.