6 Ways to Fix Windows Defender Service Access Denied Error

Did you encounter a Windows Defender service access denied error? Here is all you should know.

Windows Defender is one of the most popular antivirus programs, protecting millions of computers against vicious threads. However, many users report that their Windows Defender cannot be started.

Often, when users try to start Microsoft’s built-in antivirus, an error message appears on the screen informing them that the service couldn’t be started. There are a few ways to fix this.

Why can’t the Windows Defender service be started?

Many Windows 10 users reported that the Windows Defender service wouldn’t start on their PCs. Here are a few reasons why this may happen:

• Incompatible antivirus – Some users prefer third-party antivirus. If the choice does not work well with the built-in Windows Defender, you may expect this error.
• A corrupted account – Your login account may be corrupt and will trigger this Windows Defender service access denied error.
• Corrupted app files – If the app files are bad, you will also not be able to start its services, leading to the error.

Moreover, here are some other similar issues that users reported:

• Windows Defender service won’t start in Windows 11, 10, 7 – Even if you don’t use Windows 10, you should know that almost all of our solutions are compatible with older versions of Windows, so feel free to try them.
• Windows Defender service won’t start error 577 – Sometimes, error 577 can appear while trying to start Windows Defender service. To fix this problem, ensure you don’t have any third-party antivirus installed on your system.
• Windows Defender Security Center won’t open – Several users reported that Windows Defender Security Center won’t open or work at all. To fix this issue, check if you have the latest updates installed.
• Windows Defender service won’t start access denied – This problem can appear due to issues with your permissions. To fix the problem, you need to adjust the security permissions of the ProgramDataMicrosoft directory.
• Windows Defender service keeps stopping – If Windows Defender service keeps stopping, the issue might be profile corruption. Create a new user profile and check if that solves the problem.

How can I fix the Windows Defender service not found/access denied errors?

1. Disable and remove third-party antivirus solutions

Running two antivirus solutions at the same time causes various technical issues. Use dedicated software removal tools to eradicate any third-party antivirus files.

For example, IObit Uninstaller is an excellent choice. This tool can remove all unwanted programs with their associated files, leaving no trace behind, as IObit will scan and display logged programs, folders, registries, etc, to delete them with just a right-click.

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2. Install the latest Windows Updates 

1. Press Windows Key + I to open the Settings app.
2. Now go to the Update & Security section.
   
3. Click the Check for updates button.
   

Windows will now check for available updates and download them in the background. Once the updates are downloaded, restart your PC to install them.

3. Run an SFC or DISM scan

3.1 SFC Scan

1. Press Windows Key + X and select Command Prompt (Admin) or Powershell (Admin).
   
2. When Command Prompt opens, enter the following command and press Enter:
   sfc /scannow
   
3. The SFC scan will now start. The scan can take up to 15 minutes, so don’t interrupt it.

According to users, sometimes Windows Defender service won’t start because of file corruption. Your system files can get corrupted, and that can cause this error to appear.

Once the scan is finished, check if the problem persists. If the issue is still present, or if you couldn’t run an SFC scan, you might want to try running a DISM scan instead.

3.2 DISM scan

1. Press Windows Key + X and select Command Prompt (Admin) or Powershell (Admin).
   
2. When Command Prompt opens, enter the following command and hit Enter:
   DISM /Online /Cleanup-Image /RestoreHealth
   
3. DISM scan will now start. The scan can take up to 20 minutes, sometimes more, so you need to be patient and not interrupt it.

Once the DISM scan is finished, check if the problem persists. If the problem is still there or you couldn’t run the DISM scan before, repeat the SFC scan and check if that solves the problem.

4. Clean your registry

Sometimes, Windows Defender cannot be started if there are issues with your registry. For example, a corrupted registry entry can cause this issue to appear, and you need to find and remove the problematic access.

This is a complex task to perform manually, so it’s better to use special software. There are many great registry cleaners available that can help you with that problem.

To find the proper choice for this task, you can opt for efficient registry cleaner tools that eliminate residual files and optimize your PC.

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5. Create a new user account

1. Open the Settings app and go to the Accounts section.
   
   
2. Go to Family & other people on the menu on the left. Then, click Add someone else to this PC in the right pane.
   
3. Click I don’t have this person’s sign-in information.
   
4. Now select Add a user without a Microsoft account.
   
5. Enter the desired user name and click Next.
   

After creating a new user account, switch to it and check if the problem is still present. If not, you might have to change to the newly created account and start using it instead of your old one.

6. Perform an in-place upgrade

1. Download Media Creation Tool from Microsoft’s website and run it.
2. Select Upgrade this PC now, and click Next.
   
3. Wait while setup prepares the necessary files.
4. Select Download and install updates, driver, and optional features (recommended), then click the Next button.
   
5. Follow the instructions on the screen until you reach the Ready to install screen.
6. Make sure that Keep personal files and apps appears on the recap list. If not, click Change what to keep and select Keep personal files and apps from the list.
   
7. Follow the instructions on the screen to complete the installation.

Once the installation is finished, you’ll have a fresh installation of Windows, and the problem should be resolved.

Not being able to start the Windows Defender service can be a problem, but we hope you managed to fix this issue with one of our solutions.

You might be also interested in our guide on what is MsSense.exe and how to fix its errors because it’s the executable of Microsoft Defender for Endpoint.

Before you leave, you can also check our guide on what to do if you can’t access the Windows Defender Scans folder.

Note that we have not made these solutions in any particular order, so you should try what seems the most appropriate.