Many users of the Windows operating system, which brings with it Windows Defender antivirus system, have reported about the Windows Defender error code 0x800b0100

Is that the case for you, and you are eagerly looking for a fix? Then, you have come to the right article for that, as here we are going to cover all that information. Starting from what the issue is and what is causing it, to the solutions you will need to fix it. 

Now, Windows Defender is something that a lot of PC users use to protect their computer systems from virus attacks. This works fairly well and will do the job, for the most part, to keep your computer safe. 

Problems arise when this software does not work properly and starts showing error messages like this. But you will be able to fix that by yourself with the instructions that we have given here. 

Probable Causes of the Windows Defender Error Code 0x800b0100 

Before we start listing all the solutions that you are going to need to fix the problem, it is going to be really important to go over the possible causes of this issue. 

With a good understanding of the problem, you will be able to understand and implement the solutions to this issue much more easily. Along with that, you can work around any technical glitches that you might have caused accidentally. 

  • First, we must point out that the most common cause of this issue is corrupt system files. Being important systematic inclusions for the proper performance of Windows Defender, corruption here will cause error code to come up. 
  • It can either because of covert virus attacks, or improper downloading of update files. Anything like this has the potential to cause error code problems, including this one. 
  • Then, if you have other antivirus software running in the system, that can cause error code problems by means of conflict. This is especially bad because of the fact that none of the antiviruses will work properly. 

Again, if there is some kind of a technical glitch within the Windows Defender service that is another very pertinent cause of this issue. So, these are the primary reasons behind this error code issue. 

4 Solutions for Windows Defender Error Code 0x800b0100 Problem 

Now it is time to go ahead and list the 4 solutions to fix the Windows Defender error code 0x800b0100. If you know the exact cause of the problem, you will be able to apply the solutions right away. 

But if not, then apply the solutions one after the other to fix the problem. 

Diagnose the Windows Defender Service 

The Windows Defender service has to be active in order for the antivirus to function properly. So, here is how you can check for that. 

  • Open the Windows Run dialogue box by pressing both the Windows key and the R key. 
  • In that dialogue box, type in services.msc into the text panel and press the Enter key to proceed. 
  • You will now come across a list of options regarding working programs. Look for the Windows Defender in that list and click on it. 
  • Now, in the new window that comes up set the Startup Type to the Automatic setting. Ensure that the service condition is Started
  • Look for the Windows Advanced Threat Protection Service option after this and select it. Then, select the Windows Defender Network Inspection Service and click on it. 

After you have carried out all of the steps from above, you are now good to check if the Windows Defender is working or not. 

Perform an SFC Scan 

The System File Checker scan can be a very useful thing if you are facing this particular error code issue. Here is how you will be able to run the SFC scan in your computer system. 

  • Boot up your computer system and after that click on the Windows Start button. 
  • In the search section over there, type in ‘command prompt’ and press the Enter key. 
  • Click on the Command Prompt option from the list of results that come up. That is going to open up the said window. 
  • Right-click on that option and then select the Run as Administrator option. Type in the password to execute the process. 
  • Now, as the Command Prompt window is active, type in sfc/ scannow and press the Enter key. 

Now, the scanning is going to start and you will have to wait till it completes. Then, you will be able to fix the problems from thereon. 

Use the DISM Feature 

If you are facing the Windows Defender error code 0x800b0100 issue, then you can use that to fix this problem. Here is how you will be able to do that. 

  • Hold down on the Windows key on your keyboard and then press the X key. 
  • From the list of options that come up from there, select the Command Prompt option. Make sure you have admin access for that. 
  • Now, as you are in the Command Prompt window, type in the dism.exe /Online /Cleanup-image /Restorehealth commands. 
  • Press the Enter key to start the process. 

You will have to wait for some time before this process completes. And once it is then you can check if it is working or not. 

Carry Out a Clean Boot of the System 

Performing a clean boot of the system is going to ensure functioning even with technical glitches. Doing this is also going to bypass any third-party application that might be causing the problem. 

To do this, here are all the steps that you will need to take. 

  • Launch the Windows Run dialogue box by tapping on the Windows key and the R key. 
  • In the text entry section, type in msconfig and then press the Enter key after that. 
  • Now, a window is going to come up and click on the Services tab in it. 
  • Look for the Hide All Microsoft Services option and click on the checkbox next to it. Click on the Disable All button after that. 
  • After this, click to expand the Startup tab and then click on the Task Manager option. 
  • Choose the Disable option after selecting one item that appears from the Task Manager
  • You will have to individually repeat these steps for each item on the list. And as you are done with all that, close Task Manager
  • Click on the OK button in the System Configuration window. 

As you are done with all this, you will have to restart the computer. Then, you are good to go ahead and carry out the next part of the process. 

  • Open up the Run dialogue box once again and in the text entry panel, type in msconfig. Press the Enter key after that. 
  • As the configuration window comes up, click to expand the General tab. In that, look for the Normal Startup option. 
  • Now, select the Services tab from here and in it, uncheck the Hide all Microsoft Services option. 
  • Look for the Enable All option and click on it. Then, click on the Startup tab to expand it and select the Task Manager after that. 
  • Right-click and select Enable for each option that is there on the list. 

You are most likely going to get a prompt for system restart from here. If you get that confirm from there, or just restart the system yourself. 

This will very likely solve the problem for you and you will be able to use Windows Defender again. 


With the 4 methods that we have listed, you will be able to fix the problem easily. Yet, if you happen to have any questions regarding this, then you can drop that into the comments section on this page. 

A lot of users participate over there and they will be able to clarify your doubts easily. If you want articles just like this one, then you can find that out on our website. All our guides are comprehensive as this one and will help you fix problems yourself.