How to fix Windows Defender Quick Scan not working in Windows 11

If Microsoft Defender’s Quick Scan stops partway through or won’t start at all on Windows 11, first check that you’re launching it from the right place in Windows Security. If it still fails, restart your PC, close any other antivirus program that’s running, and install the latest Defender protection updates. Then restart and run the scan again.

What Quick Scan does and why it matters

Microsoft Defender Antivirus comes built into Windows 11 and protects against malware such as viruses, ransomware and spyware. Its Quick Scan checks the places on your PC where malware is most likely to hide.

A Full Scan examines every file and program on the device, so it takes much longer. Quick Scan is the recommended option because it finishes faster and still gives you a good level of protection. When it fails, you lose the easiest way to check your PC.

Run Quick Scan the correct way

Before you try any fixes, make sure you’re starting the scan from the right screen.

1. Open the Start menu and search for Defender.
2. Select Device protection.
3. Click Manage in Windows Security.
4. Check that you’re on the Virus & threat protection page in Windows Security. If you aren’t, select it from the menu on the left.
5. Click Quick scan.

The scan should start and show an estimated time to finish. It usually takes less than two minutes, though it can take longer if you have a lot of data stored on your PC.

Restart your PC

If Quick Scan still won’t run, restart your computer and try the steps above again. This sometimes fixes the problem, but not every time.

Close any other antivirus program

Another antivirus product running at the same time can get in the way of Defender. Here’s how to check:

1. Open Windows Security and go to Virus & threat protection.
2. Under Who’s protecting me?, select Manage providers.
3. Look for any other known antivirus provider in the list.
4. If you find one, right-click its icon and choose Exit or Close.
5. Run Quick scan again.

You can turn the other antivirus back on once the Quick Scan has finished, if you want to.

Install the latest Defender protection updates

If Microsoft Defender Antivirus is out of date, installing the latest protection updates gives it current security intelligence, engine and platform updates. Automatic updates sometimes fail to download, so checking manually makes sure the latest patches and bug fixes are installed.

1. In Windows Security, on the Virus & threat protection page, click Protection updates.
2. Click the gray Check for updates button.
3. Let Windows finish checking for updates and follow any on-screen instructions.
4. Look for a new update and check that the Version created on date has changed.
5. Restart your PC.
6. Run Quick scan again.

After the restart, Quick Scan should run normally.

Frequently asked questions

How long should a Windows Defender Quick Scan take?

It usually takes less than two minutes. It can take longer if you have a lot of data stored on your Windows 11 PC.

What’s the difference between Quick Scan and Full Scan?

Quick Scan checks the places where malware is most likely to hide, while Full Scan examines every file and program on your device. Quick Scan is the recommended option because it’s faster and still gives you a good level of protection.

Do I have to keep my other antivirus turned off?

No. You only need to close it while the Quick Scan runs, and you can turn it back on once the scan is done.