Can't Turn On Windows Defender. How To Fix It?

Can't Turn On Windows Defender On Windows 10. How To Easily Fix It?

Windows Defender is an antivirus program and a fully integrated part of Windows 10. It offers real-time protection from various threats such as adware, spyware, and viruses. Windows Defender is fast and efficient, not wasteful of system resources, and one of the most widely used antivirus programs. To protect computers, the software uses signature-matching scanning to compare potential viruses against a database of known threats. It also uses analysis, which monitors software and other attributes to find new malware or threats that rapidly change code to avoid detection. Anything that is flagged as suspicious is sent to Microsoft for further analysis.

Windows Defender runs in the background, but you can 'snooze' it if you do not wish to be interrupted. You can also scan individual files or do full scans. Defender also scans new drives that are connected to your computer. If you are running the latest version of Windows 10, you have a capable protection set with various useful tools and minimal impact on system performance. Windows Defender has an excellent 'look and feel' within the operating system, providing adequate defence for your computer.

One of the possible reasons for users being unable to turn on Windows Defender is third-party antivirus software installed on their Windows operating systems. Other reasons for this issue might be malware infections, software conflicts (possibly with another antivirus program), a corrupted registry, etc. In this guide, we present several possible solutions to this problem so that you will be able turn on Windows Defender.

cant turn on windows defender. how to fix it

Table of Contents:

Restart Windows Security Center Service

Windows Services (also know as services.msc) are used to modify how Windows services run on your system. These services are responsible for running available programs and managing many system settings and resources. You can modify a service's settings for security, troubleshooting, and performance-related reasons. You need to access Windows Services to stop the Security Center service. Windows Security Center service monitors and reports security health settings on the system. The health settings include firewall, antivirus, anti-spyware, Windows Update and Internet settings. To restart this service, type "run" in Search and click the "Run" result.

restart windows security service step 1

In the Run dialog box, type "services.msc" and click "OK" to open Windows Services.

restart windows security service step 2

In the Services window, find "Security Center" service and right-click on it. Select "Restart" from the drop-down menu.

restart windows security service step 3

Another way to restart the Windows Security Center service is to select "Properties" in the drop-down menu when right-clicking on this service. In the Properties windows, find and click "Stop". Wait a few seconds until the service has stopped, click "Start", and it will be started again.

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Uninstall Third-Party Antivirus Software

If there is any third-party antivirus software installed on the Windows operating system, Windows Defender will probably detect it and shut itself down. It is usual practice to have multiple security software packages installed on a system - this will create conflict between them. Therefore, consider uninstalling any third-party antivirus software if you want Windows Defender to work properly. After you have uninstalled third-party antivirus software, type "windows defender" in Search and select the "Windows Defender settings" result.

uninstall third-party antivirus software step 1

In the Windows Defender settings window, click "Open Windows Defender Security Center".

uninstall third-party antivirus software step 2

Now, click "Virus & threat protection".

uninstall third-party antivirus software step 3

Click "Virus & threat protection settings".

uninstall third-party antivirus software step 4

Ensure that "Real-time protection" is on - this locates and stops malware from installing or running on your device. If it is turned off, toggle the switch to the "On" position to turn it on.

uninstall third-party antivirus software step 5

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Update Windows

You can also try to update the current version of Windows installed on your system. Checking for updates for the entire Windows operating system might also help. An outdated Windows operating system could cause the Windows Defender issue (not being able to turn it on). Latest signature updates are necessary for Windows Defender to keep your computer secure. Try checking for Windows Updates and then also update Windows Defender itself. To update Windows, type "windows update" in Search and click the "Check for updates" result.

update windows step 1

Now, click "Check for updates". If there are any updates available, install them. If there are any updates pending (as in our example), click "Restart now" - Windows will restart the computer and install the updates.

update windows step 2

When the Windows update process has finished, update Windows Defender. To do this, type "virus" in Search and click the "Virus & threat protection" result.

update windows step 3

Now click "Protection updates".

update windows step 4

Finally, click "Check for updates". See if this solves the issue with not being able to turn Windows Defender on.

update windows step 5

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Run The SFC Scan

System File Checker (SFC) is a utility in Windows that allows users to scan for corruptions in Windows system files and restore them. This guide describes how to run the System File Checker tool (SFC.exe) to scan your system files and to repair missing or corrupted system files (including .DLL files). If a Windows Resource Protection (WRP) file is missing or corrupted, Windows might not behave as expected. For example, some Windows functions might not work, or Windows might crash. The "sfc scannow" option is one of several specific switches available with the sfc command, the Command Prompt command used to run System File Checker. To run it, first open Command Prompt first by typing "command prompt" in Search, right-click on "Command Prompt", and then select "Run as administrator" from the drop-down menu to run Command Prompt with administrator privileges. You must run an elevated Command Prompt to be able to perform a SFC scan.

run the sfc scan step 1

In opened Command Prompt window, type "sfc /scannow" and press Enter on your keyboard to execute this command. System File Checker will start and should take some time to complete the scan (about 15 minutes). Wait for the scanning process to complete and restart your computer to see if you still have issues with turning Windows Defender on.

run the sfc scan step 2

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Perform A Clean Boot

When you start Windows by using a normal start-up operation, several applications and services start automatically, and then run in the background. These programs include basic system processes, antivirus software, system utility applications, and other software that has been previously installed. These applications and services can cause software conflicts. A clean boot is performed to start Windows by using a minimal set of drivers and start-up programs. This helps eliminate software conflicts that occur when installing a program or an update, or when running a program in Windows. To perform a clean boot, type "system configuration" in Search and click the "System Configuration" result.

perform a clean boot step 1

In the System Configuration window, click the "Services" tab and then mark the "Hide all Microsoft services" checkbox. Click on "Disable all".

perform a clean boot step 2

Then, click the "Startup" tab and click "Open Task Manager".

perform a clean boot step 3

Under the Task Manager Startup tab, select the first application and click "Disable" to disable it - disable all applications one-by-one, repeating this step. Once you have disabled all programs, close Task Manager and click "OK" in the the System Configuration Startup tab and restart the computer. Check to see if this fixes the issue with not being able to turn Windows Defender on.

perform a clean boot step 4

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Scan Your Computer For Malware

There might be malware infections on the system and causing Windows Defender issues. We suggest you scan the system for viruses and see if this solves the problem. Some malware removal tools are detailed below. You will need to start your computer in Safe Mode to successfully scan the system. Safe Mode is a diagnostic start-up mode in Windows operating systems used to obtain limited access to Windows when the operating system does not start or function normally. It is the reverse of 'Normal Mode', which starts Windows in the usual manner. One of the most common steps to take when troubleshooting a system is to boot into Safe Mode. Safe Mode starts Windows in a basic state, using a limited set of files and drivers. It can help to troubleshoot problems on your computer. Read this article to find out how to start a computer in Safe Mode. 

Use one of these malware removal tools to scan your Windows operating system for possible infections:

Microsoft Safety Scanner

Microsoft Safety Scanner is a free downloadable security tool that provides on-demand scanning and helps to remove viruses, spyware, and other malicious software. You can download it here

Malwarebytes

Malwarebytes offers a 14-day trial of their Premium edition, which provides Real Time Protection and can act as a full antivirus suite. Malwarebytes claim that they built their product to be compatible with other antivirus software including Windows Defender. You can download Malwarebytes here

Emsisoft Emergency Kit

Emsisoft Emergency Kit is another free on-demand scanner that is portable. This means you can store it on a USB drive and scan a system offline. You can download Emsisoft Emergency Kit here

Zemana Anti-malware

Zemana Anti-Malware is effective malware detection and removal software that protects users from malware, spyware, adware, ransomware, rootkits and bootkits. You can download Zemana Anti-Malware here

We hope that one of the above solutions solves the problem with not being able to turn on Windows Defender. As well as the above methods, you could also simply restart your computer. Sometimes a simple restart can solve the issue.

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About the author:

Tomas Meskauskas

I am passionate about computer security and technology. I have an experience of 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an editor for pcrisk.com since 2010. Follow me on Twitter to stay informed about the latest tech news or online security threats. Contact Tomas Meskauskas.

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