13:58:16 min/gen Error: You are trying to install an older version than the one currently installed. If you really want to install such a version, please uninstall the current version first.
Well, your avast is updated and you're trying to install an old manual update.
08:21:13 min/gen Return code: 0x20000004 [Cannot connect to download354.avast.com (unknown:80).]
Any firewall? Any other security program installed? Parental control? Try to use "No proxy" into avast update settings.