Windows Security Unexpected Error
Windows Security Unexpected Error is an error in Windows Security Center that usually prevents users from accessing the virus and threat protection features. Such problems may involve Windows Defender, Firewall, or other security settings that affect the system’s protection capabilities. When you encounter this error, you may wonder why this happened. This error may be caused by the following reasons:
- Damaged system files: If critical Windows system files are damaged, it may affect the normal operation of Windows Security Center.
- Third-party antivirus software conflicts: Some third-party security software may conflict with Windows Defender and cause this error.
- Windows Update Issues: Not installing the latest Windows Updates may cause security features to not function properly, including this error.
- Incorrect registry settings: Incorrect configuration of certain registry keys can affect the operation of Windows Defender.
How to Fix Windows Security Unexpected Error in Windows
Here are some ways to fix unexpected error in Windows Defender. Let’s take a look at the specific steps.
Method 1: Check for New Windows Updates
Updates released by Microsoft may contain fixes for known bugs or vulnerabilities in Windows Security Center. Some Windows components may have problems due to old versions. Updates ensure that Windows Security is compatible with other parts of the system.
Step 1: Right-click the Start button and choose Settings.
Step 2: Click Update & Security > Windows Update.
Step 3: Hit the Check for updates button to search for the new updates.
Step 4: If there is a new available update, click Download & install to get it.
After the Windows update is installed, check if the problem still exists.
Method 2: Check and Repair Corrupted System Files
Corrupted system files may lead to some problems, including Windows Security unexpected error. In this case, you can check and repair these damaged files to fix this error. Here are the steps.
Step 1: Type cmd in the Windows search box, right-click Command Prompt, and choose Run as administrator.
Step 2: In the UAC window, click Yes to open the utility.
Step 3: Type DISM.exe /Online /Cleanup-Image /Restorehealth and press Enter.
Step 4: When the previous step completes, type sfc /scannow and press Enter.
Wait patiently for this process to complete, and go check if this error disappears.
Method 3: Uninstall the Third-Party Antivirus Software
Some third-party antivirus software may conflict with Windows Defender (Microsoft’s protection software) or other system functions, causing the system to run slowly or abnormally.
Step 1: Type Control Panel in the Windows search box and press Enter.
Step 2: Change the view to Large icons or Small icons from the View by drop-down box.
Step 3: In the following list, choose Programs and Features.
Step 4: Find the software you need to remove and right-click it to choose Uninstall.
Follow the on-screen instructions to complete the process.
Method 4: Modify the Windows Defender Registry Key
Some security software or malware may change Windows Defender’s registry entries, causing it to not work properly. Manually modifying the registry can help restore normal functionality.
Step 1: Press the Win + R keys to open the Run dialog.
Step 2: Type regedit in the box and press Enter.
Step 3: Navigate to the following place:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender

Step 4: Click the Windows Defender key and select New > DWORD.
Step 5: Type DisableAntiSpyware in the name box.
Step 6: Right-click the DisableAntiSpyware DWORD and choose Modify.
Step 7: Input 0 in the Value data box and click OK.
Method 5: Reset the Windows Security App
If none of the above work, you can try resetting it. When the Windows Security app won’t open, crashes, or displays an error message, resetting it can restore default settings and fix software corruption.
Step 1: Press the Win + I keys to open the Settings app.
Step 2: Select Apps > Apps & features.
Step 3: Scroll down the list to find and click Windows Security.
Step 4: Click Advanced options to enter the next page.
Step 5: In the Reset section, click Reset. In the pop-up prompt, click Reset to apply the change.
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Final Thoughts
Several methods, including updating Windows, repairing system files, modifying the Windows Defender registry key, and so on, are listed in this article. When you encounter this error, use them one by one to fix it.
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