How to fix
“Unexpected Error”
on Windows

Hello. I tried to use Windows Defender to run a scam but I received a message saying "Unexpected Error." What could be the problem?

Windows Defender or Microsoft Defender Antivirus is an anti-malware component of Microsoft Windows. It provides some basic functions when it comes to operating system security. It can warn users about malware[ref en-1] infections and other cybersecurity threats.

When Windows Defender first came out, it only protected users from spyware. Now, people can feel safe when using Windows without third-party antivirus software. However, sometimes people run into issues when trying to use it. Users report receiving an "Unexpected Error" when trying to run a scan. The full message reads as follows:

Threat service has stopped. Restart it now.

Unexpected error. Sorry, we ran into a problem. Please try again.

While it is unknown what exactly could cause the Windows Defender to produce this error, we prepared 6 steps that could help you fix it. The problem is suspected to appear because of missing updates, third-party antivirus interference, or the Security Center service.

Manual troubleshooting can become a lengthy process, so you can also use a maintenance tool like [d1] that can fix most system errors, BSODs,[ref en-2] corrupted files, and registry[ref en-3] issues. Otherwise, follow the step-by-step instructions below.

Method 1. Install Windows Updates

• Type Updates in Windows search
• Click Check for updates and wait till the process is finished
• If optional updates are available, install them too

• Once done, restart your system

Method 2. Fix Corrupted System Files

Use Command Prompt commands to repair system file corruption:

• Open Command Prompt as administrator
• Use the following command and press Enter:
  sfc /scannow

• Reboot your system
• If SFC returned an error, then use the following command lines, pressing Enter after each:
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth

Method 3. Uninstall Third-Party Security Software

Your third-party antivirus program could be interfering with Windows Defender, resulting in an error. We suggest you try to uninstall the software and see if the issue disappears.

• Go to Apps & Features
• Find your antivirus in the list and click on it
• Press Uninstall and finish the process

Method 4. Restart the Security Center Service

• Press Windows key + R to open the Run box
• Type services.msc and hit Enter
• In Services, search for Security Center
• Right-click on Security Center and click on Restart

Method 5. Change Registry Key Values

• Press Windows key + R to open the Run box
• Type Regedit and press Enter
• Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
• Change both DisableAntiSpyware and DisableAntiVirus values to 0 by double-clicking
• If the keys are not showing, right-click on an empty space, select New, and click on DWORD (32-bit) Value
• Name the key DisableAntiSpyware and set the value to 0

• Do the same for DisableAntiVirus

Method 6. Perform a Repair Upgrade

• Download the Windows 10 ISO file from the official Microsoft website
• If you agree to the license terms, select Accept
• On the What do you want to do? page, select Create installation media for another PC and then select Next

• Select the language, edition, and architecture (64-bit or 32-bit) for Windows 10
• In Select which media you want to use, Select ISO file then click Next
• Select the download location then click Save
• Windows 10 ISO file will be downloaded
• Right-click Windows 10 ISO file and click Mount
• Open Setup.exe
• To get important updates, select Download and install updates
• Ensure that Keep personal files and applications is checked
• Click on Install to start the upgrade