problem with downloaded file signature

[buzinga]

Hi
I have this problem that comes from time to time
I set my patch my pc to update apps after downloading the apps sometimes the security solution Pop's up saying
that the installer signature is invalid "lets say something like vlc " so i stop the update process
the re initiate it, the second or third attempt downloads the correct file

I suspect like MIM attack or just a faulty connection

but there should be built in  like hash checker or signature checker before starting the installation process
by patch my pc to ensure the integrity of the downloaded application