UPDATE: We have released a dedicated article describing avast! and Windows 8 / 8.1 compatibility issues. Containing also solutions/fixes to resolve them. You can find it here or in the top menu.

Apparently lot of avast! users are having compatibility issues after upgrading operating system to Windows 8.1. What usually happens is that avast! will completely disappears, and Windows will start saying you’re not protected. Then you’re being offered a Windows Defender, which is better than nothing but definitely not that good as avast! antivirus.

Download avast! Internet Security 2014

Luckily we have a simple fix for you. All you have to do is to get the latest avast! antivirus 2014 (version 9) which is fully compatible, and even certified to work on the Windows 8.1. Procedure depends whether you have already upgraded to Windows 8.1 (see point 1), or if you’re still running on some of it’s previous versions where avast! is working fine (see point 2).

1) Already Upgraded to Windows 8.1

If you have already upgraded to Windows 8.1 your avast! probably disappeared completely or it’s having a compatibility issues. Follow these steps to get avast! back working, and protecting your computer

  1. If you have any other antivirus software installed (e.g. Windows Defender), uninstall it
  2. Download the latest version of avast! – Free Antivirus, Pro Antivirus, Internet Security, or Premier
  3. Install it using our guide ‘How to Install avast! Free Antivirus 2014
  4. That’s it, avast! version 2014 is fully compatible with the Windows 8.1

2) Still Running on Windows 8

If you’re still running on Windows 8, and you’re just about to upgrade to Windows 8.1 update your avast! antivirus first to avoid any future compatibility issues. Simplified steps are listed below or you can check our full guide ‘How to Update Your avast! Antivirus to 2014

  1. Open your avast! user interface
  2. Go to ‘Maintanance’ tab
  3. Click on the button ‘Update Program’
  4. After the update process will finish, restart your computer
  5. That’s it, you can now safely upgrade to Windows 8.1

This solution is however available only for the core products - avast! Free Antivirus, avast! Pro Antivirus, avast! Internet Security, and avast! Premier. If you’re running any of the avast! corporate products – avast! Endpoint Protection (Plus), avast! Endpoint Protection Suite (Plus), or avast! (File/Email) Server Protection, you have to wait for an official program update. According to Che Johnson at Official avast! Forum, Head of EDU Support at AVAST, such update should be available within a month or so.

This article has 16 comments | Did we miss anything? Just let us know in the comments!

  1. Michelle Reply

    So, if I paid for the more expensive Avast anti-virus and it’s gone due to the fact that I upgraded to Windows 8.1, do I then have to buy it again? My computer is six months old and so was the Avast.



  2. Norbert Reply

    Uninstalling Windows Defender completely cannot be done, only to turn it off. I’ve already upgraded to Windows 8.1, and would like to have avast back. But still a bit confused after reading some stories regarding to this (blue screen after avast install, Windows cannot be started, login not possible to Windows anymore). I don’t want to kill my laptop or my OS, but would like to have avast back. So is the option turning off Win Defender a 100% solution? Thank you in advance!

  3. IvanBaker Reply

    OKplus will not work with my windows 8.1 unless I disable the Avast antivirus. Can okplus be allowed to pass the antivirus software? How can I do this?
    Ivan Baker

  4. Leslie Davis Reply

    I bought a new Dell latop that came with Mcafee, which I have now uninstalled. It is on windows 8. I use Google Chrome

    I have Avast antivirus on my old laptop.

    I have been trying for several days to download avast, the paid one, It downloaded then said it was not compatible with my computer. Still waiting for an anser from Avast

    Then so I would have something I tried to download the free version. I just cant get it to download.

    I want to upgrade to windos 8.1, but thought I should get the antivirus right first.

    Do i have to turn off windows defender?

  5. Raul Reply

    Keeps crashing with the Endpoint versions, as Avast is installed when you restart Windows no longer loads. Even down the latest version of the web and recently installed Windows 8.1, Avast! endpoint is still killing the OS on the first reboot.

  6. Larry Reply

    I’m having the same problem. I am running Win 8.0 and the latest version of Avast! antivirus, and have tried to upgrade to 8.1 (at least 6 times!)on my new HP computer, but each time, was told that I first had to delete Avast!.

    I did uninstall Avast! every time I tried to upgrade (using the Windows store) and still no luck. It’s apparent from all the forums I’ve read on this issue, I’m certainly not alone with this problem.

    I’ve read that MS is (supposedly) going to change Windows Update, to allow for the update that way, but even though I check for updates daily, nothing has changed to allow me to update to 8.1. Maybe I’m lucky without knowing it, as I’ve read that many people who have managed to upgrade to 8.1 say they’re now having all kinds of problems with the new OS.

    Is it just that MS can’t fix this issue, or just doesn’t care enough to be bothered by our complaints?

  7. Nancy Reply

    I have Win 8.1 and ‘thought’ I had avast internet security (it is running on another machine with Win7 and license is good for 3 machines. Come to find out avast disappeared and Windows Defender took over (shows what I know….). Avast hasn’t replied to two inquiries yet :( . I’m a little nervous to disable WD and install avast (although I have downloaded it) as it seems like there is a chance it gives more troubles. My subscription is up the end of April and I was going to renew — but now I’m thinking of just letter WD take over. Does anyone have opinions on WD vs Avast Internet Security? Really disappointed avast hasn’t replied and further disappointed that I paid for the protection only to find it disappeared sometime back without any notice from avast. Perhaps my bad (being unaware) but if my version wasn’t compatible with the Win 8.1 upgrade, it seems like avast should have let me know and also let me know when they made avast compatible — not just take my money and take away avast without notice. And then NOT reply to inquiries in a timely manner. Not too pleased right now….

  8. Loi Reply

    Please Help! I used to be windows 8 PC HP2000 when i first bought and got upgraded to 8.1. I haven’t had issues for awhile until now. I keeps getting errors 0x8000CCC90 messages. I read on other sites that inorder to fix this problems is to Uninstalled Avast! I did all that and still keeps getting errors on my email when try to send/received messages on my windows live mail. This driving me crazy for the last 2 days now.

  9. Rajinder Singh Reply

    I need HELP!!!!!
    The avast key I have is till 2038. And the new version of avast says that the key has expired. On my previous windows XP, I used to install the old version(8.0.1489) which supports the key, and then upgrade the programme to the latest version without any issues. But Win 8.1 is not allowing me to install older version(keeps saying that there is compatibility issues). I have tried making it compatible thru win xp/vista/07/08, but still no luck. Could you please HEEEEEELLLLLLPPPPP me to install the older version(8.0.1489)….

    Thanks in advance.

    • getavast.net Reply

      Hi Rajinder,

      The avast! key you are using is probably cracked as there is no official key valid until 2038. We suggest to use the latest version and get your free key here.

  10. Rajinder Singh Reply

    Thanks for your response. I have am just wondering if the older version can be made compatible for windows 8.1 ? Also I saw in a different forum a key was cracked that was showing valid until 2095. damn!!!!. Can u please get me a key then. Sorry I am unable to find one here.

    Thank you. !!!

  11. Rajinder Singh Reply

    Well I have found something. I have got key upto 2099!!!! Yes 2099. Please let me know if it can be posted here…

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