This is the useful error message that my mother got when trying to upgrade Free AVG 2015 on windows 10.
To skip to the end of the story look for a utility called AVGRemover on their site – it will uninstall all AVG products cleanly allowing new ones to be installed.
I was called on to help. To start with it was using the latest installer to upgrade. It goes most of the way through the process (including a reboot) then fails with the title message.
OK, so the next attempt was to uninstall the previous version. This turned out to be more tricky than needed since the avgagent service fails to uninstall with the cryptic message that you do not have enough permissions to uninstall it.
Repeat running the uninstaller as admin, same result.
Attempted to stop the avgagent service as admin – still prevented.
Searches of the avg forum found a help operator had suggested using another utility (which failed to work even for the questioner).
Only when the feedback form had been given a detailed list of the problem did it provide a link to the uninstaller.
This is not a very friendly experience for an end user (or indeed an experienced software developer). If AVG know that there uninstaller fails enough that they put a repair utility on the site at least have the decency to link to it directly.