Windows Defender won’t update [BEST FIXES]

Milan Stanojevic
by Milan Stanojevic
Deputy Editor
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  • Windows Defender often fails to update and meet your expectations. Don’t hesitate to correct that.
  • For example, you can manually install update definitions. Moreover, feel free to run an SFC scan.
  • For similar tips, don’t hesitate to take a closer look at this Security & Privacy Software section too.
  • Lastly, simply bookmark our Windows 10 Troubleshooting Hub. You may find it useful in the future.  
Windows Defender won’t update solutions

A good number of Windows users have raised concerns that Windows Defender won’t update on their computers.

Most of these queries have to do with Windows Defender failing to update virus definitions, and this usually happens when their internet connection is good.

Sometimes even the Windows Update feature is affected as it fails to update the system.

While using Windows Defender, you may receive a message with regards to definition updates when opening the service, or when you try to check for updates and it says they cannot be checked, downloaded, or installed.

Windows Defender is the default, pre-installed antimalware software built into Windows 10 OS, to protect users from malware.

This includes adware, viruses, worms, Trojans, Rootkit, Backdoor, ransomware, and spyware, among other emerging threats.

In this case, the service should work well in the background notifying users of any detected malware or when something is wrong.

In some cases, however, you may come across issues such as this, when Windows Defender won’t update, or the update fails. Usually, there are three ways to update it:

  • From the Windows Defender Update Interface
  • From Windows Update
  • From Manual Download via the Microsoft Malware Protection Center (MMPC) website

If you’re experiencing the Windows Defender won’t update the issue, try the solutions listed below to resolve the issue.

If your computer is part of a company network, or it is managed by an admin, they’ll configure updates through local network drives or set policies to update after approval. Check with your network admin first.


We’ve written extensively about Windows Defender issues before. Bookmark this page in case you need it later.


What can I do if Windows Defender won’t update?

  1. Try out a different antivirus solution
  2. Preliminary fixes
  3. Manually install update definitions
  4. Verify that you have all required Windows Update files
  5. Set Windows Defender service as automatic
  6. Run an SFC Scan

1. Try out a different antivirus solution

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When Windows Defender fails to meet your expectations, it’s time to consider using an alternative. Well, if you want to forget all about update errors, then do try it out Vipre.

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2. Preliminary fixes

take a look at preliminary fixes

  • Check if you have other security software installed, as these will turn off Windows Defender and disable its updates. Uninstall your current anti-malware software.
  • Check for updates in Windows Defender Update Interface and try Windows Update if it failed. To do this, click StartProgramsWindows Defender>Check for Updates Now.
  • Install all updates that may be pending and restart your computer, then try the Windows Defender update again. Set Windows Defender to automatically get updates (it gets this as part of Windows Updates).
  • Run Windows Update troubleshooter.

3. Manually install update definitions

install update definitions

  1. Go to the Windows security portal.
  2. Follow the instructions to download and install the definition updates.
  3. If you cannot install manually or still get update errors, there are other things hindering it so contact Microsoft tech support for further assistance.

Microsoft usually delivers updates through Windows Update, Automatic Updates, or Windows Server Update Service (WSUS).

In some cases, Windows Defender won’t update because of problems with these services. In this case, update the definitions manually, as described above.

If you were able to install updates manually, the issue is caused by a Windows Update problem.


Don’t know how to solve Windows Update issues? Just make sure to use one of these great tools!


4. Verify that you have all required Windows Update files

Windows Update files

  1. Open the Windows Update website.
  2. Install all recommended updates.
  3. Review the Windowsupdate.log file for error messages by clicking Start, then type %windir%windowsupdate.login the Search box, and then press enter.
  4. Go to Windows Help and How-to web page and enter the keywords describing the problem from the log file you found.

5. Set Windows Defender service as automatic

  1. Right-click Start and select Run.Windows Defender won’t update
  2. Type services.msc and press Enter.
  3. Right-click Windows Defender antivirus service.Windows Defender won’t update
  4. Click Properties.
  5. Ensure that Service Status is running.Windows Defender won’t update
  6. Ensure Startup type is Automatic (if not, select Startup type as automatic and click Start).Windows Defender won’t update
  7. Click Apply then click OK.

Windows Defender service won’t start? Check out this detailed guide to fix the problem in no time!


6. Run an SFC Scan

  1. Click Start.
  2. Type CMD in the search box.
  3. Right-click Command Prompt and select Run as Administrator.Windows Defender won’t update
  4. Type sfc/scannow and press Enter.Windows Defender won’t update

This will check whether there are corrupted system files that cause Windows Defender not to update. To do this,

Let us know if any of these solutions worked when Windows Defender update failed. Just leave a comment in the section below.

Editor’s Note: This post was originally published in April 2018 has been since revamped and updated in October 2020 for freshness, accuracy, and comprehensiveness.

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