Windows Defender is one of the world’s most widely used antivirus systems, guarding millions of computers against malicious threats. Unfortunately, many customers complain that they are unable to launch Windows Defender. An error message stating that The service couldn’t be started displayed when customers attempt to launch Microsoft’s built-in antivirus.
This error occurs when the Windows Defender service is turned off or when a related registry key in the Windows Registry is damaged. So, you can use these quick troubleshooting methods in this article to fix the issue and launch Windows Defender to safeguard your PC.
How to Fix the Windows Defender “The Service Couldn’t Be Started” Error
Given below are four methods you can use to solve the Windows Defender (Error 0x8007139f)
- Set Windows Defender Service to Start Automatically
- Repair the WMI Repository
- Change Windows Defender Registry Value
- Disable Third-Party Antivirus Solution
You will need an administrator account to execute these suggestions
1] Set Windows Defender Service to Start Automatically
If the Windows Defender Service is down, Windows Defender may stop functioning. With the Services app, you can check the current state of the service. If the service is stopped, make it start automatically and check if it fixes the problem.
This is how you set up the Windows Defender service to start automatically:
- Press the Windows key + R to open the Run dialogue box. Type services.msc and click OK.
- In the Services window, scroll down and locate Windows Defender Firewall. Next, right-click on it and select Properties from the context menu.
2] Repair the WMI Repository
A set of requirements called Windows Management Instrumentation (WMI) enables you to control many Windows environments, including Remote Systems. If the WMI has failed, you can repair it, which can fix the Windows Defender—The service couldn’t be started—error.
- Right-click the Windows logo and choose the Windows Terminal (Admin) option.
- Enter the following command to switch folders where the WMI repository is located.
c:\windows\system32\wbem
- Copy and paste the following command and press Enter:
dir /b *.mof *.mfl | findstr /v /i uninstall > moflist.txt & for /F %s in (moflist.txt) do mofcomp %s
- Continue to execute the following commands:
Net Stop winmgmt C: CD %SystemRoot%\System32\wbem RD /S /Q repository regsvr32 /s %SystemRoot%\system32\scecli.dll regsvr32 /s %SystemRoot%\system32\userenv.dll for /f %%s in (‘dir /b /s *.dll’) do regsvr32 /s %%s scrcons.exe /regserver unsecapp.exe /regserver winmgmt.exe /regserver wmiadap.exe /regserver wmiapsrv.exe /regserver wmiprvse.exe /regserver mofcomp cimwin32.mof mofcomp cimwin32.mfl mofcomp rsop.mof mofcomp rsop.mfl for /f %%s in (‘dir /b *.mof’) do mofcomp %%s for /f %%s in (‘dir /b *.mfl’) do mofcomp %%s
Check whether the Windows Defender error code has disappeared.
3] Change Windows Defender Registry Value
If the Windows Defender service is disabled in the Windows Registry, this error can occur. You must change the WinDefend key and Start value to enable Windows Defender.
Note: Before proceeding, create a system restore point or take a registry backup. If you accidentally delete something you should not, it will help you restore.
- Open Registry Editor and navigate to the location given below:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinDefend
The next step is to take complete control over the WinDefend registry key. If you do not take ownership, you will get denied error access or cannot edit Start. Here is how to do it take full control of WinDefender:
- Right-click the registry key WinDefend under Services in the left pane of the Registry Editor and select Permissions.
- On the Permissions for WinDefend window, click on the Advanced button.
- In the Advanced Security Settings for WinDefend window, click on the Change link next to Owner to change the owner.
- In the Select User Group window, type Administrators under the Enter the object name to select. Click OK.
- This will send you back to the Advanced Security Settings window. Next, double-click on the Administrators option under Permission entries.
- In the Permission Entry for WinDefend window, check whether Full Control under Basic permissions is enabled.
So, that is it! Now you have taken full ownership of the WinDefend registry key.
- Now, navigate to the Registry Editor window. On the right side of the window, right-click the Start value and click on the Modify option from the context menu.
- This will open the Edit DWORD Value pop-up window.
- Type 2 under the Value data field and click OK to save the changes.
Close the Registry Editor, then restart your PC. Launch Windows Defender after the restart and look for any improvements.
4] Disable Third-Party Antivirus Solution
Antivirus, anti-malware, and firewall software from third parties can frequently conflict with Windows Defender and cause more harm than good, like causing this error. If your Windows PC has any third-party security programs installed, you must remove them immediately.
To solve the problem, check whether you have another antivirus software installed. Your Windows PC might come pre-loaded with one, even if you have not installed one. Hence, if you have one, use Control Panel and the Settings app to remove the antivirus software.
When uninstalling the security software, please remove it from the system tray. Also, uninstall any browser add-ons and other security-related extensions. After removing it, restart your PC and check for any changes.
Conclusion
Windows Defender can stop working if the associated services do not function. Restarting the service and enabling it to run automatically manually is possible. You can change the Start value of the Windows Defender key in Registry Editor to enable the service and resolve the error.
So, I hope one of the methods helped you resolve the problem of being unable to start the Windows Defender service. It would be best if you attempted the most appropriate solution for you, as these solutions are not arranged in any specific order.
