Fix Widows Defender Error 0x800700AA The service couldn’t be started

Some Windows 10 users are reporting that they always get the 0x800700aa when attempting to run a Windows Defender scan on Windows 10. While some users are reporting that the issue only occurs when running Windows Defender while others see this error code at every attempted startup.

Windows Defender 0x800700aa

After looking at this issue thoroughly, it turns out that there are several different underlying causes that might be triggering this error code. Here’s a list of potential culprits that might be responsible for the apparition of the 0x800700aa error code:

  • System file corruption – As it turns out, in most documented cases, this particular error code appears if certain OS dependencies required by the Windows Defender utilities are affected by corruption. If this scenario is applicable, you should be able to fix the issue by running SFC and DISM scans in quick succession. Under more serious circumstances, you might only be able to fix the issue by triggering a clean install or repair install procedure.
  • 3rd party application conflict – Under certain circumstances, you might expect to see this error occurring due to some kind of conflict between a 3rd party process or service and Windows Defender. In this case, you can resolve the issue by booting your system into safe mode and starting Windows Defender while there’s no 3rd party interference.

Now that you are familiar with every potential culprit that might be responsible for the apparition of the 0x800700aa error code with Windows Defender, move down to the next potential fix below:

Method 1: Running SFC and DISM scans

As it turns out, by far the most common culprit for this particular issue is some kind of system file corruption that is affecting Windows Defender files that are being called into action when a scan for a new version is initiated.

Some users that we’re also seeing the 0x800700aa issue have managed to resolve it by running a couple of utilities designed to fix logical errors and system file corruption – DISM (Deployment Image Servicing and Management) and SFC (System File Checker).

These two tools operate similarly, but our recommendation is to burn both in quick succession in order to maximize your chances of resolving the 0x800700aa.

SFC (System File Checker) replaces corrupted files by using a local archive to replace corrupted instances with healthy copies, while DISM relies on the WU component to download healthy copies to replace bad data.

Note: Generally, DISM is better at fixing OS-related components, while SFC is better at fixing logical errors.

Here’s a quick guide on running both an SFC and DISM scans from an elevated CMD window in order to resolve the 0x800700aa error with Windows Defender:

  1. Start by opening up a Run dialog box by pressing Windows key + R. Inside the Run window, go ahead and type “cmd” inside the text box, then press Ctrl + Shift + Enter to open up up a Command Prompt with admin access.
    Opening a Command Prompt window

    Note: When you’re prompted by the UAC (User Account Control), click Yes to grant administrative privileges to the CMD window.

  2. When you’re inside the elevated CMD window, type the following command and press Enter to initiate a DISM scan:
    exe /online /cleanup-image /scanhealth
    Dism.exe /online /cleanup-image /restorehealth

    Note: Keep in mind that DISM needs a reliable Internet connection in order to download healthy copies that will be used to replace corrupted files. The ‘scanhealth’ command will initiate a scan to look for system file inconsistencies, while the ‘restorehealth’ command will replace any inconsistencies that are found from the first scan.

  3. Right after the first scan is finished, reboot your computer and continue with the steps below.
  4. Once your computer boots back up, follow the instructions at step 1 again to open up another elevated CMD window. But this time, type the following command and press Enter to initiate an SFC scan:
    sfc /scannow

    Note: This scan operates at a kernel level, that’s why it’s important not to close or interrupt this scan after you initially start it. If you interrupt the process prematurely, you run the risk of creating further logical errors that might spawn other errors down the line.

  5. Finally, after the second scan is complete, restart your computer and see if the issue is resolved at the next system startup.

If the same 0x800700aa error with Windows Defender is still occurring, move down to the next method below.

Method 2: Enabling Windows Defender in Safe Mode

If running DISM and SFC scans didn’t fix the issue in your case, there’s a big chance Windows Defender is throwing this error due to some kind 3rd party conflict that is affecting certain system file dependencies used by the built-in antivirus suite.

Some users dealing with the same 0x800700aa error (either at startup or when the utility is launched) have reportedly managed to fix the issue by boosting their computer in Safe Mode and enabling the security suite while the system was not permitted to run any 3rd party processes and services.

While booting in Safe Mode, your Windows is configured to load the bare minimum processes – Safe run will not run autoexec.bat, config.sys files, most drivers, dedicated graphics drivers, 3rd party processes, etc.

If you suspect that a driver or 3rd party process is interfering with Windows Defender, follow these instructions to boot your Windows 10 computer in safe mode.

After you have successfully booted in Safe Mode, repeat the action that was previously causing the 0x800700aa error and see if the issue is now fixed.

Note: If this operation allows you to enable Windows Defender, the change should be carried over when you boot your system normally.

If the same problem is still occurring in safe mode when you attempt to enable Windows Defender, move down to the next potential fix below.

Method 3: Refreshing every Corrupted Windows 10 Computer

If none of the methods above have worked for you, it’s very likely that you’re dealing with some type of underlying system file corruption that is triggering the 0x800700aa error when attempting to launch Windows Defender.

In this case, the only thing you can do is to reset every relevant OS component that’s related to your current Windows installation.

In order to do this, there are 2 different methods that will allow you to do this:

  • Repair installThis is hands-down the best way of resetting every relevant Windows component because it allows you to do this without touching any of your personal files present on the OS drive. However, that the main disadvantage is that this procedure is quite tedious and you’ll be required to use compatible installation media to perform this operation.
  • Clean installThis is by far an easier procedure because it can be initiated directly from the GUI menu of your Windows 10 installation. However, unless you manage to back up your data in advance, expect to lose every personal data on the OS drive (applications, games, personal media, documents, etc.)
Kevin Arrows
Kevin is a dynamic and self-motivated information technology professional, with a Thorough knowledge of all facets pertaining to network infrastructure design, implementation and administration. Superior record of delivering simultaneous large-scale mission critical projects on time and under budget.

Expert Tip

Fix Widows Defender Error 0x800700AA The service couldn’t be started

If the issue is with your Computer or a Laptop you should try using Restoro which can scan the repositories and replace corrupt and missing files. This works in most cases, where the issue is originated due to a system corruption. You can download Restoro by clicking the Download button below.

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