Are you having issues with Windows Defender not working on Windows 10? This may lead to virus or malware attacks on your PC or data loss. This article offers effective methods to help you run Windows Defender again.
I’m experiencing a critical issue where Windows Defender immediately crashes about 5 seconds after opening. Why is my Windows Defender not working? How can I fix it? Do you guys have any recommendations?
Microsoft Defender, built into Windows, protects your device against malware, ransomware, and other threats in most cases. However, it is sometimes inevitable that issues may arise, such as Windows Defender won't open, Windows Defender not allowing APP to run, and so on. In this guide, we will focus on Windows Defender not working on Windows, providing causes and practical, step-by-step fixes.
Below are the most prevalent reasons:
Fixing Windows Defender not opening/working/running doesn’t require advanced technical knowledge in most cases. You can first try restarting your computer. If this does not work, you can dive into the step-by-step fixes below.
One of the most frequent reasons for Defender issues is interference from other antivirus programs. Windows is designed to avoid running multiple security tools simultaneously. To address this:
Microsoft Defender depends on specific background services to function. If these services stop running, the application may fail to start. Follow these steps to restart them:
Step 1. Press Win + R to access the Run dialog, type services.msc, and hit Enter.
Step 2. Locate Microsoft Defender Antivirus Service, right-click on it, and select Restart.
Step 3. You should also ensure its startup type is set to Automatic.
You can also check related services such as Windows Security Service and Security Center. Restarting these services can often resolve temporary glitches and restore full functionality.
Running an outdated version of Windows can easily lead to the Windows Defender not working on Windows 11/10 issue. Microsoft frequently releases updates that fix bugs, patch vulnerabilities, and improve compatibility.
Step 1. Open Windows Settings, and then navigate to Update & Security.
Step 2. Click on Windows Update, and then hit Check for updates.
Step 3. Follow the on-screen guide to install all available updates and restart the PC.
Corrupted system files are another common culprit of Windows Defender not open. Fortunately, Windows includes built-in tools to detect and repair these files.
Step 1. Search cmd in the Windows Search box to open Command Prompt with admin permissions.
Step 2. Type the command sfc /scannow and press Enter. The scan may take 10–20 minutes. Do not close the terminal until it finishes.
Step 3. If SFC finds and repairs errors, run these commands one by one:
Step 4. After the scans finish, restart your PC to apply repairs.
Step 5. Open Windows Security and check if real-time protection is enabled.
Sometimes, Microsoft Defender is disabled through the Windows Registry. This can happen due to malware, system tweaks, or leftover settings from other software.
Step 1. Press Win + R, type regedit, and press Enter. Then, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender.
Step 2. In the right pane, look for DisableAntiSpyware. If it exists, double-click it and set its value to 0.
Step 3. If the value doesn't exist, right-click the empty space in the right pane > New > DWORD (32-bit) Value, name it "DisableAntiSpyware," and set it to 0.
Step 4. You can also check additional registry keys by navigating to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Real-Time Protection. Ensure no DWORD values like DisableRealtimeMonitoring are set to 1. If found, set them to 0.
In some cases, like Windows Defender not working after reset, Group Policy settings may prevent Defender from running. This is more common on professional or enterprise versions of Windows. To check and modify these settings:
Step 1. Press Win + R, type gpedit.msc, and press Enter.
Step 2. Navigate to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus.
Step 3. Look for Turn off Windows Defender Antivirus on the left, double-click it, and set it to Not Configured or Disabled.
Step 4. Apply the changes and restart your system.
While fixing Windows Defender not working restores your real-time protection, it’s important to know that no single security tool is 100% foolproof. Ransomware, phishing attacks, and zero-day vulnerabilities can bypass even the best antivirus software. To ensure comprehensive data safety, pair your working Windows Defender with a robust backup and ransomware protection solution like AOMEI Backupper.
AOMEI Backupper is not an antivirus replacement, but it adds a critical layer of defense by ensuring you can always restore your data, even if Defender fails to block an attack. Together, Windows Defender and AOMEI Backupper create a "dual protection" strategy that covers both prevention and recovery.
Step 1. Click on Backup on the main interface of AOMEI Backupper, and choose a backup option, such as System Backup, to create a system image.
Step 2. Head to Tools > Ransomware Protection.
Step 3. Enable Ransomware Protection by toggling the switch, and check the sub-options as needed, then click OK to save the settings.
Don’t worry if your Windows Defender is not working. Here are the most effective solutions to fix this issue. To make sure that your data is always safe, you can try to use Microsoft Defender with AOMEI Backupper together.
With AOMEI Backupper, you can create system backup, transfer files from PC to PC, clone disk to disk, and so on.