Avast antivirus updating
Please update your Avast antivirus settings as described below 1.
Many users have rightfully complained that Blue Stacks runs slow when their PC is also running the Avast antivirus.
Avast slows down Blue Stacks due to one of its settings.
Quickly fix PC issues and prevent others from happening with this software: This error appears due to a conflict between Avast and your current antivirus program.
So, just disable your current antivirus (in most cases this is Windows Defender) and try to install Avast again. This error will remind you that having two antivirus programs installed on your computer is not a good thing.
If Avast still won’t open, you can also use the solutions suggested to fix Avast update issues.