So if Windows will not update you remove it ?
I would consider this seriously. But fortunately in the last 20 years Windows never asked me to do a "clean install" due to update problems. And of course it's much more difficult to switch the OS instead of switching from one free virus scanner to another one.
If the avast software isn't updating it doesn't mean the problem is avast.
It can be other software you have installed causing the problem.
You are right!
But good programmers would be a lot more gassy than quitting an update job with nothing more than "unkown error..good bye". There is no such thing like an "unknown error". This is really poor programming style from the middle ages of IT. You can always tell where you are, what you tried to do and what failed. You might not know the reason, why you failed, but you know what you've been doing while crashing. Communicating an "unknown error" with no more hints is a lack of quality, that makes me frighten. What about the quality in other areas of the Avast program?