Hi.
Don’t know whether any users have noticed this issue. It seems that the above update causes trouble to computers. In my case stated in topic ‘Disk 0 Master Boot Record can’t be scanned, Error Code 32’, the corresponding update affected my Window 10 is KB4493509.
https://forum.avast.com/index.php?topic=226531.msg1501618#msg1501618
When I search more today, it seems that many web articles suggest the affected areas(not restricted to window 10 and KB4493509 only) is much larger than I think.
https://borncity.com/win/2019/04/12/avast-and-avira-confirms-april-2019-update-issues/
Honestly, I do not have enough expertise to distinguish whether they are fake news or not, but my trouble with KB4493509 is true. Just open a new topic in case users decide to delay updating their window till a valid solution comes out.