Windows Defender is the security component of the Windows Operating System. It was introduced in the latest version of Windows to eliminate malware and other viruses. Ordinarily, it is free from bugs. However, users can still experience Windows Defender Error Code 0x8007139f.

About Windows Defender Error Code 0x8007139f

Windows Defender is turned off whenever a third-party security software is installed. As a result, users may notice that their Windows Defender could not be started and result in the error code 0x8007139f

In general, users can face this error when these software starts interfering with Windows Defender. 

Some other common causes of this error are:

  • Windows Defender program service not running 
  • Corrupted system files 
  • Malware attack 
  • Interference with anti-malware or anti-spyware programs 

Fixing Windows Defender Error Code 0x8007139f

To begin with, the Windows Defender error code 0x8007139f is easy to resolve. Before you head over to the possible solutions, try the following quick fixes – 

  • Run a full system scan 
  • Disable third-party security software 
  • Remove anti-malware or anti-spyware program 
  • Update to the latest Windows OS 
  • Turn on Windows Firewall 

If these fixes work in resolving this particular error, then you do not need to head further. However, if the issue remains, follow the solutions mentioned below one by one.

Solution 1 – Run System File Checker 

Windows operating systems have an in-built system file checker. It can automatically scan and fix corrupted system files on the computer. 

Follow these steps to run this program on your system. 

  1. Click on the Search button next to Start. Type ‘cmd’. 
  2. Right-click and select ‘Run as Administrator’. Next, type ‘sfc /scannow’ and press Enter. 
  3. Finally, restart your system after the command has executed.

Solution 2 – Check Windows Defender Service 

Generally, a malware or virus infection can turn off some important Windows services. As a result, Windows Defender may not be able to start as its service is turned off. 

Therefore, you need to check whether it is running or not by following these steps;  

  1. Click on the Search button. Next, type ‘services.msc’ and click on it. 
  2. Find Windows Defender and double-click this service. 
  3. Here, you’ll find an option for ‘Startup type’. Click and change it to Automatic. Click Ok. 
  4. Next, right-click on the service and select Start. 
  5. Restart your computer. 

Solution 3 – Fix Windows Defender Registry Keys 

Another way to fix Windows Defender error code 0x8007139f is by fixing its registry keys. Besides, this process is very simple and easy to follow in the given steps. 

  1. Initially, make a backup of ‘HKEY_LOCAL_MACHINE’ before doing any changes.
  2. Click on the Search button. Type ‘notepad’ and press Enter. 
  3. Copy and paste the following statements – 
  • Windows Registry Editor Version 5.00


“DisplayName”=”@%ProgramFiles%\\Windows Defender\\MsMpRes.dll,-103”


“Group”=”COM Infrastructure”







“Description”=”@%ProgramFiles%\\Windows Defender\\MsMpRes.dll,-3068”








































  1. Consequently, click on the Save As option. Here, go to Save as type and choose ‘All Files’. 
  2. Rename this to ‘fixing.reg’ and save it. Close the notepad. 
  3. Lastly, navigate and execute fixing.reg.  
  4. Restart PC. 


To summarize, following the fixes stated above, the Windows Defender error code 0x8007139f should be resolved from your system. In addition, you can post your queries or share additional information in the comments section below.