Alex Ruben
How To Fix Quick Scan Not Working in Windows 11/10 Quickly
If your Windows Defender Quick Scan isn’t doing its job or just hangs when you try to run it, you’re not alone. Sometimes, Windows gets weird about its built-in security, and quick scans just refuse to kick off or respond. Fixing this is pretty crucial since Defender keeps your machine safe from malware, so it’s worth digging into a few tweaks to get it back on track. Usually, it’s just some services or settings messing around, or corrupted system files hiding somewhere. Luckily, most fixes don’t need a full OS reinstall or anything drastic.
How to Fix Windows Defender Quick Scan Not Working
Check if Defender Service is Running
Sometimes, Defender’s core service isn’t running, which means the quick scan can’t even start. It’s annoying because Windows should keep this running automatically, but occasionally it gets stuck, disabled, or software conflicts kill it.
- Press Windows + R and type
services.msc, hit Enter. - Scroll down to Microsoft Defender Antivirus Service — if it’s not set to Automatic, double-click and change it. If it’s stopped, click Start.
- Make sure the status says Running and the startup type is set to Automatic.
On some setups, this service could be turned off after Windows updates or third-party security software messing with it. If you notice that service stopped again after a reboot, check your startup items or security software conflicts.
Adjust Registry Settings to Enable Defender
Sometimes, Windows policies prevent Defender from working properly, especially if you turned off some settings manually or via group policies. This is where editing the Registry can fix the weird blocking.
- Open regedit with admin rights—search it from the start menu, right-click, & choose Run as administrator.
- Before diving in, back up your registry: File > Export — pick a safe location, name it, set range to All, and save. Because of course, Windows has to make it harder than necessary.
- Navigate to:
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender - Look through the right panel for keys like DisableAntiSpyware or anything set to
1. If you spot them, double-click and change the value to0. - If you’re unsure what a key does, just keep notes — messing with registry can cause problems if you go overboard.
- Close regedit and restart your PC. Hopefully, that’ll let Defender’s Quick Scan run properly now.
On some machines, this registry tweak is all it takes to fix stubborn issues. But, yeah, always back up — no one wants a brick, right?
Run DISM and SFC to Fix Corrupted System Files
If Defender still goes dark, system files might be broken. Windows has built-in tools for this — DISM and SFC — that repair corrupt or missing system components. They’re kinda like fixing a leaky pipe by replacing the broken parts behind the wall. Not sure why it works, but it does.
- Open Command Prompt as admin (Windows + X > choose Windows Terminal (Admin) or Command Prompt (Admin))
- Run this command and wait patiently:
DISM /Online /Cleanup-Image /RestoreHealth. It scans your system and pulls files from Windows servers if needed — can take several minutes. - Once done, run:
SFC /scannow. It’ll check your system files for errors and automatically repair them if possible. Expect some reboots during or after.
If these tools find and fix issues, it might be enough for Defender to start working again. Worked on a few PCs where corruption had broken the entire security system.
Extra Tips & Common Problems
Keep your Windows updated in Settings > Update & Security > Windows Update. Developers patch bugs like this all the time. Also, avoid installing more than one antivirus because they tend to clash—Windows Defender can get disabled or confused if other security software is fighting for control.
And if you’re manually disabling Defender in registry or group policies, double-check those settings are correct and revert if needed. Sometimes, malware or other apps intentionally disable security features, so give your machine a good scan with another tool if problems persist.
Wrap-up
Fixing Defender isn’t always straightforward, but most issues revolve around services, registry settings, or corrupted system files. Once those are sorted, the quick scan usually kicks back into gear. Just some steps that might save a lot of headaches—like, your system security depends on it.
Summary
- Check and restart Defender service.
- Review and modify registry keys that might disable Defender.
- Run DISM and SFC to fix possible file corruption.
- Keep Windows updated and avoid conflicting security software.
Fingers crossed this helps
If all of that didn’t fix it, maybe dig deeper into event logs or consider reinstalling Windows or resetting Defender settings. Either way, these are the most common fixes that get most folks back in business. Hopefully this shaves off a few hours for someone, or at least points in the right direction.