Troubleshooting Windows Defender error 0x800700AA – The service couldn’t be started

A corrupted system file may cause Windows Defender to fail to start automatically and display an error message with the following description:

Windows Defender
Service could not be started.
The requested resource is in use.
Error code: 0x800700aa.

A manual launch also has no effect. Read the steps below to fix Windows Defender error 0x800700aa.

What causes Windows Defender error 0x800700AA?

Damaged files in the system: This can happen to system files as well as any installed program. Conflicts arise that prevent us from using applications normally or even opening them, such as Windows Defender error 0x800700aa. read more

Core Isolation Memory Integrity that failed to enable has been fixed

This problem may apply to several computers, but in my case, it was an issue with my new Laptop. Even after unpacking, I was unable to activate memory integrity for kernel isolation. The screenshot above shows that it was due to an incompatible driver. In the latest Windows 10 updates, you can click on the blue link to see a list of incompatible drivers.

In most cases, the incompatible driver is wdcsam64_prewin8.sys, the Western Digital driver included in Windows 10. If you click the link and wdcsam64_prewin8.sys appears in the list, follow these steps to remove this driver if it is not needed on your system. read more