Fix Virus Definition Failed in Avast Antivirus

Do you see the ‘virus definition failed’ error when you try to update virus definitions and you tried everything but, the error persists? In this blog, we have provided easy fixes for virus definition failed errors, and here is a fix for ‘Virus Definition Failed’ in Avast Antivirus.

For beginners, Avast Antivirus is an internet security software created by Avast for Microsoft Windows, macOS, Android, and iOS. Avast Antivirus offers free and premium versions that include computer security, browser security, antivirus software, and anti-spam protection.

Why does the Virus Definition Failed error occur in Avast?

In most situations, this problem is caused by an update or repair defect that Avast company had previously fixed with version 6.16. So, for a quick and hassle-free resolution, upgrade your Avast Antivirus to the most recent version available.

If the program is not getting updated, it’s most likely because some files have gotten corrupted. In this instance, you can use the Avast built-in troubleshooter to enable the application to repair itself.

Fix Virus Definition Failed in Avast Antivirus

Fix Virus Definition Failed in Avast Antivirus

Now that we know of the possible reasons for this error to occur, let us discuss the solutions on how to fix the Virus Definition Failed error in Avast Antivirus.

Method 1: Update Avast Antivirus software

Most users claimed that they experienced this problem, even though they had updated Avast to version 6.16. After a detailed examination, we found that the issue arose due to a faulty date involved in the update. Although the update was installed properly and the virus protection signature was up-to-date, the faulty date caused the Virus Signature Update Mechanism to display an error.

Follow these steps to update Avast with the correct date:

  1. Click on the Menu icon in the Avast Antivirus app.
  2. Select the Settings menu.
  3. Select the General tab from the list of primary tabs displayed on the Settings panel.
  4. Finally, click the Check for updates and check if the correct date is set in the Update sub-tab. Now, wait for the process to finish.
  5. Restart your PC and verify if the virus definition failed error is fixed.

Method 2: Repair Avast Antivirus

The ‘Virus definitions update failed’ error might also be caused by a partially damaged Avast program. In some cases, the error message reads, Downloading of VPS failed. Mostly, the problem arose either because of an unexpected computer shutdown or because a security scanner kept corrupting particular objects during the update process.

If this situation applies to you, you can resolve the virus definition failed problem by utilizing the Avast troubleshooting options to repair itself.

Here are the simple steps to repair the Avast application via its built-in troubleshooter:

  1. Open Avast and Navigate to the Action menu located at the top right corner.
  2. Select Settings > General tab.
  3. From the sub-menu, choose Troubleshooting.
  4. Scroll down to the Still having problems section of the Troubleshooting tab, now Select Repair app.
  5. When the confirmation message appears, choose Yes. Then, wait for the scan to finish.
  6. Once the scan is complete, select Resolve all to resolve all the issues that were discovered during the scan.

This should fix all problems within Avast, and you should be able to enjoy the virus-free & error-free functioning of your computer.

Also Read: How to Remove Avast from Windows 10

Method 3: Reinstall Avast

If all else fails, reinstalling the Avast app should definitely get rid of all minor glitches, bugs & also, virus definition failed error. Here are the steps on how to do it:

1. Open the Run box by pressing Windows + R keys together.

2. To launch Uninstall or change a program, type “appwiz.cpl” in the Run box and click OK.

type appwiz.cpl in the Run box and click OK | Fixed: ‘Virus Definition Failed’ in Avast Antivirus

3. Right-click on the Avast folder and choose Uninstall.

Select Avast Free Antivirus and select Uninstall.

4. After you’ve deleted Avast, go to the official website and download the latest software version.

Reinstalling Avast isn’t the best approach, but if the built-in repair mechanism doesn’t work, you’ll probably have to do it anyway.

Note: In some cases, you may want to install an older version of the program until the flaws in the newest version have been resolved.


We hope that this guide was helpful and you were able to fix virus definition failed error in Avast. If you have any queries/comments regarding this article, then feel free to drop them in the comments section.

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