23rd October 2016, 12:19
FYI, i have KDE Neon Plasma 5.8.2 in a VB VM, & i had already installed Synaptic therein several weeks ago. Just now i launched my VM, launched Synaptic, picked a random application in it & clicked its "Visit Homepage" link. That same error msg as originally reported, popped up. Once i dismissed it [3x needed, it kept repeating], i then opened Firefox & tried the link again. This time it worked ok.