So I installed Windows 10 Technical Preview yesterday and I’m really enjoying it so far, but I came to my first major hurdle when trying to install Avast. It won’t install due to an incompatibility. 
I’ve tried installing it in compatibility mode with no success.
Is there a beta available I could download and test? I would be very appreciative of any support.
I’m sure there will be further input, but I doubt any peripheral security software developers will be spending much time with W10 at this point.
I don’t know how you would keep up with the constant Code injection\modification by MS to the W10 core while developing further.
5 minutes after a preview version is released and you expect AV to be compatible :
it is now that work may begin
avast will work when the OS is ready to be released
Forgive my insolence, but EVERYTHING else I’ve installed has been compatible with the single exception of antivirus. But, considering MSE was also incompatible, I’m sure this will be the norm for now.
I would hope that Avast will eventually put out a beta I can test with W10. Fingers crossed!
The same thing happened with win8 technical preview - MS blocked anti-virus applications other than those approved ones - at technical preview launch that was only windows defender (which was part of the OS installation).
So I don’t see this being any different for some time.
Avast had early program updates for win8, but was still blocked by MS.
Follow up:
Both Avira and AVG were compatible for installation.
While I DEFINITELY prefer Avast, I need SOME sort of protection for now… so, Avira it is (for now).
I find this interesting and would like further info, I Quickly looked on both Avira and AVG forums but didn’t spot anything,
Let us know how this works out over time.
If you know of others posted in forums that have achieved successful install and consistent operation of these AV’s I’d be interested in a link.
Will keep you posted.
Be wary. Just because an anti-virus does not fail to launch when installed on Windows 10 does not mean it will provide you with the same level of protection it would under Windows 8… though some protection is obviously better than none. The same sort of relationship exists with all other software and drivers that you might use on Windows 10.
As a rule, until Windows 10 is listed as officially supported by a given application be very wary of potential problems… and, in the case of security software, of developing a false sense of security.
Edit: and if they claim to have full support for Windows 10 before Windows 10 is officially released be even more wary (suspicious even). Because Windows 10 itself will be constantly changing until it is released claiming full support for it before that time would be quite foolish on the part of the developers.
Avast will also cause issues with connectivity. DO NOT UNINSTALL ANY OTHER NETWORK ADAPTORS if you have any i.e Tungle, VPN as you will be in a world of poo. Avast blocks Gateway settings etc and you can not flush it you will no have NET regardless. the only way to fix this on windows 10 is to do the repair in recovery option in pc settings. uninstall all apps e.t.c. tried for hours upon hours. (Limited Connectivity / No Default Gateway ). Comon problem updating from windows 7 - 8 and also windows 8 - 8.1
UNINSTALL AVAST before you UPDATE to windows 10. also run the removal tool. I will wait for avast to have some compatibility as it is well worth the wait and I will just stay away from fishy sites and torrents.
Same problem here. Installed Panda for now. I do hope Avast is fixing the “problem” 
Fixing what? It’s almost impossible to get any third party software to work on
something that isn’t even developed enough to be reliable. You need to be reasonable
enough to know that MS could make code changes which would make any third party
software unusable. At least wait until Win10 is in beta stage.
As far as Avira and AVG go, I wonder about their effectiveness on an unstable platform. ???
The replies of some above imply they are just upgrading their main Windows setup with the Win 10 TP.
My God, people, what are you thinking?
This is not a new release of Windows. It’s a Technology Preview. It’s not stable. It’s not trustworthy. It’s not even beta software. It’s just a development build. And it’s going to expire.
You want to test Win 10, great, more power to you - but treat the system you test it on as A COMPLETE THROWAWAY.
I would suggest testing it on a virtual machine or at most a physical computer that you had laying around and that had absolutely no use before - certainly not as an upgrade to your working system!
You DO know it’s going to expire on April 15, 2015, and almost certainly not be upgradeable to the actual release, right? Many people were surprised that Windows preview versions expired (and they lost their programs and data) last time with the Win 8 previews.
-Noel
Upgrading is ridiculous. I totally agree with you NoelC (Amazing). It is however not the totally the unstable OS you make it out to be.
Some of us have been beta testing Windows 9 for quite a while and Windows 10 is still Windows 9 renamed.
It’s been around for some time.
Do not however upgrade your current OS to what is still not a finished product and, may need to be replaced when the final version is released.
Run it on a separate partition on your hard drive or on a virtual machine.
Think what you want but base code in Windows 10 is Windows 8.1 with some adds. So thats why most of the programs work. I got all my 40 programs running on Windows 10 but not Avast, just saying.
If you want to know more about Windows 10, you might want to check the following thread:
https://forum.avast.com/index.php?topic=156141.0
For info on Windows 8 - 8.1 and Threshold:
https://forum.avast.com/index.php?topic=85094.0
I installed Windows over a Clone of Windows 8, with all programs intact. Avast was working properly until October 5 .
Then on booting windows 10 received this screen say.
"
Windows Defender is helping to protest your PC
The following Malware protection software couldn’t be turned on:
avast Antivirus
Windows Defender was turned on Automatically to help protect your PC. To use a different security
software, you can browse Windows Store or contact a security provider listed to get an up-
to-date version.
"
It was at this point that Avast stopped working. An was automatically deleted from my computer.
As i watch until the Orange Avast logo’s animation before starting my daily Windows 10 updates and tests.
As already mentioned, avast!, at this point, is not compatible with Windows 10.
Why would you even try MSE when Defender is included in Win 10 and IS MSE?
Defender in Windows 8 and now Windows 10 is a combination of MSE and Defender wrapped in one package.