Computer

Can’t use Windows Defender once it’s open? So you fix it

This application, also called Windows Security, is essential to keep our system safe, especially if we make constant use of the Internet, so keeping it active and working properly should be a primary task. That is why, if we encounter this problem, we must know what are the possible causes that originate it and, above all, how to solve it.

Reasons why Windows Defender won’t open

If, like every day, we turn on our computer regularly and everything seems to work correctly. We entered the Windows Security section to perform a system scan, but we checked with amazement how it closes or crashes, making it impossible to use. This can leave us unprotected, so we may be concerned about the situation.

That this happens is not something usual and can be due to several reasons. The most common is due to a software conflict caused by having another type of antivirus installed that is preventing Microsoft’s security system from running correctly due to incompatibility. It can also happen that we have any type of vital file for its use that is corrupted and prevents its proper functioning, as well as an incomplete installation of the system that ends up causing this failure.

The truth is, whatever the reason for this problem, it can be quite annoying and even dangerous, so we are going to see different actions that we can take to try to solve it.

Steps to fix the problem

Next, we are going to see different ways by which we can put an end to the problem that Windows antivirus does not start correctly and we cannot use it.

If there is another antivirus, uninstall it

As we have commented previously, the main cause why this error can happen is because we have another antivirus installed on the computer, making it impossible to use it. That is why it is convenient in the event that we have some other security system such as Norton, Kaspersky, McAfee, etc., we must uninstall it to see if this solves the problem.

For this, it is likely that the antivirus has its own uninstaller inside its folder, but we can always use the operating system’s own tool to uninstall it. To do this, just type Control Panel in the Start menu search box and select it. Later, in the programs section, we click on “Uninstall a program.” This will open a new window, where we must click with the right mouse button on the installed antivirus and select “Uninstall”. Later, we restart the PC and check if this ends the problem.

Check for updates

Another probable cause is a bug in some update that we have done recently. If trying to run an application or system update that could not be completed correctly may lead to the appearance of this failure. That is why we must check if there are new pending updates to help us end the problem.

Windows Update updates

To do this, we are going to press the keyboard shortcut «Windows + I» to access the «Configuration» section. Later we click on “Update and security”. And within the section “Windows Update” We check for pending updates. If so, we proceed to install them and restart the computer once finished.

Repair damaged files

Windows has its own integrated tools with which to identify and repair corrupt system files, so we must use it in case this has been the source of the problem. This tool is called SFC (System File Checker) and runs on command line. Therefore we must use the Command Prompt. To activate it we write cmd in the search box of the Start menu and click on Run as administrator.

Once its window appears, we write the following command and press Enter:

sfc/ scannow

Run SFC Scannow in Command Prompt

The process may take a few minutes, so we must not get impatient. Once finished, you will inform us if you have found any type of error.

Alternatively we can also try the command DISM (Deployment Image Servicing and Management) another system tool that is responsible for solving common problems with system applications. To do this from the Command Prompt itself, we execute the following commands individually and in this order:

  • DISM / Online / Cleanup-Image / CheckHealth
  • DISM / Online / Cleanup-Image / ScanHealth
  • DISM / Online / Cleanup-Image / RestoreHealth

Once finished, we proceed to restart the computer and check if this has solved the problem.

Use the Registry Editor

Another option that we can carry out is to make a small modification in the Registry. This is something that we must do with great care because any unwanted changes can affect the stability of the system. Therefore, it is something that we must always do under the responsibility of each user.

To enter the Editor, press the keyboard shortcut “Windows + R” and launch the “Run” command. Here, we write regedit and press Enter. Later we will make a backup in case something goes wrong having a backup. This is something that we will do by clicking on «File» and «Export». In the next window we specify “Everything in the export range”, we give it a name and the .reg format and we click “Save”.

Now we must navigate to the following route:

HKEY_LOCAL_MACHINE / SOFTWARE / Microsoft / Windows Defender

Registry Editor change value of DisableAntiSpyware

Once here we look at the panel on the right and locate DisableAntiSpyware. We double click on it and enter 0 (zero) in the Value data field. Finally, we click OK, close the Editor and restart the system. Now all you have to do is go to the “Protection against viruses and threats” section of “Windows Security” and carry out a “Quick Test” to verify that it is working correctly.

Restore Windows to a previous version

If we still can’t fix the problem with Microsoft’s antivirus, we can try revert to a previous version of Windows where it works properly. This is something that we can do without fear of losing our data, as it will offer us the possibility of keeping or deleting it before starting the restoration process.

Restore the system to a previous version

To do this, we access the Control Panel and in the upper right-hand corner in the “View by” option, we select “small icons.” Next, we click on “System” and “Advanced system settings”, located on the right side. Another window will open where we must click on “System Protection” and click on “Restore the system”.

System restore select restore point

In the new window we click on «Next» to see the restore points that we have available. We select the desired one and, finally, we click on «Next» to start the entire restoration process.

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