Officially Avast Antivirus 2017 is compatible with both Windows 8 and Windows 8.1. However, some users may have issues with running avast! on the latest Windows. This article covers the most known ones, as well as solutions for fixing them.

So far, this article covers four issues – #1 Action Center Pop-ups, #2 Blank/Black Screen#3 Impossible Avast Uninstall, and #4 ‘Process Trust’ Error during the installation.

General advise to avoid any compatibility issues between Windows and Avast antivirus is to keep both of them updated to the latest version.

According to Windows Compatibility Center, Avast antivirus 2014 is compatible. Based on 1,700 out of 1,840 users. If you’re one of the unlucky ones, we hope this article will help you to fix your problems. Listing for Avast 2017 is yet not available.

According to Windows Compatibility Center Avast Antivirus 2014 (version 9) is Fully Compatible with Windows 8 and 8.1According to Windows Compatibility Center Avast Antivirus 2014 (version 9) is Fully Compatible with Windows 8 and 8.1

Issue #1 – Windows Action Center Says Avast Antivirus is Turned Off

Apparently, this seems to be a very frequent issue. Windows 8 or 8.1 Action Center displays one of the following messages: ‘Check virus protection (important),’ ‘Windows Defender and Avast Antivirus are both turned off,’ or ‘Windows did not find an antivirus program’. Fortunately, fixing this issue is very easy.

Windows Action Center Messages Saying Avast Antivirus is Turned OffWindows Action Center Messages Saying Avast Antivirus is Turned Off

Solution #1.1 – Just turn off (pause) your Avast antivirus for 10 minutes, then re-enable it:

  • Find the orange Avast Antivirus icon in the system tray (usually it is hidden, so you need to click on the top arrow).
  • Right click on it and go to ‘Avast shields control’, select ‘Disable for 10 minutes’, and confirm.
  • Do the same to turn Avast back on by selecting ‘Enable all shields.’


Solution #1.2 – Let Windows Action Center to turn on and update Avast antivirus:

  • Go to Windows Action Center by clicking on the ‘Open Action Center’ link or the pop-up message.
  • Select ‘Turn on and update Avast Antivirus’ and Windows should start automatically updating your Avast Antivirus into the latest version.

Solution #1.3 – Reset Windows Action Center repository following these steps:

  • Open the Command Prompt as Administrator (move the mouse to the bottom-left corner, wait until the box appears, right-click on it, and select Command Prompt (Admin)).
  • In the Command Prompt type ‘winmgmt /verifyrepository’ and press Enter.
  • If you get ‘WMI repository is consistent -no problems detected,’ type ‘winmgmt /resetrepository’ and press Enter.
  • If you get ‘WMI repository is inconsistent -problems detected,’ type ‘winmgmt /salvagerepository’ and press Enter.
  • If you get ‘WMI repository has been salvaged – WMI repository has been successfully rebuilt,’  continue to the last step.
  • Restart your computer.


Issue #2 – Windows Won’t Start and Displays only a Blank/Black Screen

This issue is extremely annoying as it causes your Windows to not start and display a blank/black screen only. Users reported the issue started after they installed Avast Antivirus on their computer.


Solution #2.1 – In order to fix the blank/black screen issue follow these steps:

  • Open the Task Manager by pressing ‘CTRL’ + ‘ALT’ + ‘Delete’ simultaneously, or ‘CTRL’ + ‘Shift’ + ‘Esc’ on your keyboard.
  • When the Task Manager appears, click on ‘More details,’ then ‘Startup,’ right-click ‘Avast Antivirus,’then ‘Open file location.’
  • In the opened folder, find a file called ‘AvastUI’ and double click on it.
  • Now the Avast user interface should open, find the tab labeled ‘SECURITY’ » ‘ANTIVIRUS’ » ‘Behavior Shield,’ and find ‘Settings’ in the top-right corner of the ‘Behavior Shield’ window.
  • When the Behavior Shield settings open, un-check the option ‘Monitor the system for unauthorized modifications.’
  • Then go to the second settings tab, called ‘Trusted processes,’ add ‘C:\Windows\Explorer.exe,’ and ‘C:\Windows\ImmersiveControlPanel\SystemSettings.exe,’ and click ‘OK.’
  • Restart your computer and Windows should now start smoothly without any issues.

Issue #3 – Windows Keeps Saying to Uninstall Avast Antivirus but It’s Already Uninstalled

In some cases, even the successful uninstallation of Avast Antivirus may not be recognized by Windows. If you are experiencing this problem, try one of these steps:

  • Solution #3.1 – Uninstall Avast antivirus using the Avast Uninstall Utility.
  • Solution #3.2 – Search for ‘avast’ using the Windows search and backup, then delete all ‘avast’ files found.

Issue #4 – ‘Process Trust’ Error During Avast Antivirus Installation

This issue happens if you are trying to install Avast Antivirus on your computer running Windows 8.1, and you get the ‘Process Trust’ fatal error pop-up message saying ‘Avast doesn’t trust Avast Installer,’ and the process was disabled. Usually, this happens when you have some other security software installed, typically Malwarebytes.

  • Solution #4.1 – Disable/Uninstall any other security/anti-malware software you have installed on your computer. Then, try to run the installer again.
  • Solution #4.2 – If you have Avast previously installed, uninstall it using the Avast Uninstall Utility.

Let us Know if Your Issue is Missing or the Solutions Didn’t Work

If you are having any different problems with Avast Antivirus and Windows 8 / 8.1, just let us know in the comments at the bottom of this page. Same if the described solutions and fixes didn’t work for you.

Additional Notes

Although we have used Avast Free Antivirus 2019 screenshots in this article, these steps are also applicable for all Avast Antivirus solutions (i.e. also for Avast Pro Antivirus, Avast Internet Security, or Avast Premier) running the latest version available.

Steps are relevant for all Windows versions – Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10 (including Anniversary Update).

Written by Paul B.

My name is Paul and I love Avast since the Home Edition v4.8 (2008). I am recommending it to all my friends, but I realized they don't know how to use it. So I started this site in order to help others getting maximum from this awesome antivirus. Feel free to contact me via Facebook, comments below or this form.

This article has 92 comments | Did we miss anything? Just let us know in the comments!

  1. Fred Reply

    Have windows 8.1 and Avast premier antivirus, windows update failed to install updates.
    What is the problem and how can I get windows update to install updates?

  2. Manish Reply

    I uninstalled avast free antivirus. Now I want to install it but it’s showing some errors and is not installing. What should I do? Help me.

  3. Michael Lévesque Reply

    I don’t know what wrong with my avast, but every time i click on the icon to open the interface the icon disapear and the interface open and close without me being able to do anythink with it. Avast also disapear of the list of startup programm and won’t open automatically with windows.

  4. Dozman Reply

    Please i don’t what exactly that happen to my Avast Anti-Virus. I installed Avast in my system but it continuously telling me to go and upgrade it but any time i did, it will be telling me to purchase it with a credit card that what of $39.9. so, i don’t know how i can install this new latest that i downloaded from net. anytime i tried to install it, it won’t install correct. it continue showing me your Avast was not successfully install i.e. error. so please, i need a help on how i can do it.

  5. Andrew Gbondo Reply

    I installed avast anti virus on my computer and it work and now i want to install it on my younger brother computer it is telling me it is compatible what to do next

  6. Vrindavana Das Reply

    I have upgraded my OS from Windows 8.1 to Windows 10. I have installed a copy of the free Avast antivirus. In routine functioning, the copy of my free Avast antivirus works just fine on the system. The problem comes after registering the Free Avast Antivirus copy. Then onward, there is a conflict between my Windows 10 OS and the Avast antivirus. I am unable to roll back the system changes to a previously created restore point. Every time I perform system restore operation, it throws up an error – “system restore did not complete successfully. This is because an antivirus is running which is using a file…”

    After removing the registered copy of the Avast antivirus, or with the copy of free Avast antivirus, the system restore operation works just fine.

  7. Sally Guthberlet Reply

    I have uninstalled my Avast Antivirus program and now my laptop will not start. I am using windows 8.1. As with Hazel I have tried everything suggested as a solution, excepts reboot with a disc or restore (I did not have a restore date logged onto the computer). What can I do to repair my computer?

  8. Olu Columbus Reply

    I installed the Avast premier for a long time and it works fine on my windows 8.1. However, I just installed the Avast Secureline VPN yesterday but whenever I turn on my VPN to any Location then all my browsers would’nt connect (SafeZone, Chrome). Could you please assist? I have tried to enable rules via my Firewall but it seems I’m missing something. Regards.

  9. Debbie Reply

    I needed to restart after avast was updated it hit so far and stuck so I shut down and restarted now I have a blue screen with please wait I have removed the battery waited and started again hoping it would boot up but no just the blue screen and please wait. I’m going crazy someone please help

  10. Hazel Millar Reply

    I downloaded the free version of Avast and my Windows 8.1 laptop started to continually restart from the blue screen. I can’t get beyond this screen whether I try any of the suggested remedies such as f8, control alt delete etc. My laptop is completely dysfunctional.

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