“the stub cannot run installer / updater executable ‘C:\Program Files\ Avast Software\ Avast\setup\Sfx\instup.exe’ (code 0x3)”
Help please
- Which version of AIS…?
- OS…? (32/64 Bit…? - which SP…?)
- Other security related software installed…?
- Which AV(s) did you use before Avast…?
- 2014.9.0.2021
- Windows 10 (64)
- No
- No
Did you run the tool in safe mode…?
Yes
Redownload and try again: https://www.avast.com/uninstall-utility
did not help
Might be a bug, wait for one of the devs and/or submit a ticket: https://support.avast.com/Tickets/Submit
R you try to repair avast! then try https://www.avast.com/uninstall-utility 
How can i repair my avast?
Go to control panel>click uninstall a program> click avast! internet security>and then click on Repair option then restart your pc few times and then run avast!clean.
When i click delete avast IS in control panel, i see a message in my task bar
"you can not run this application on this computer
avast does not work in this windows version
"
You have a VERY old version of avast! IS2014.That does not support windows10,Pls update your avast! program version to new version AVAST 2015 R4 (build number 2015.10.3.2233) from this link:http://files.avast.com/iavs9x/avast_internet_security_setup.exe
After i run the app from your link, i see the error from my first post and the message from my last post ))
Pls see#12 reply and update your program.What app from my link you talking about?And see the blog post of avast! https://blog.avast.com/2015/05/06/support-for-older-avast-windows-consumer-version-will-end/