That really isn’t “trolls.” The OP does not say exactly how he went about switching Perl versions (and then, apparently, switching back ...) but it nevertheless is true that there’s a lot of package-interdependency and, within almost each and every package, a fairly substantial chunk of XS (that is, “C[++]”) code. Including, maybe, stuff that talks to the Perl interpreter’s perlguts. If there should happen to be any sort of mismatch or incompatibility there ... well, it might cause a binary-explosion or ... it might not. What it certainly could cause is, “it works in one version of Perl (on my computer, as I am running it) but not the other (ditto).” I frankly would not expect that differences between the two Perls, e.g. at a language/syntax level, would be the root-cause, i-f the package in question (taken by itself) has been certified against that version. It rings true to me.