perl 5.8

Upgrading Perl to a Modern Version: the ActiveState Guide
Upgrading Perl

Many organizations stopped upgrading Perl after the release of 5.8.8 or 5.10.1, about 8 to 11 years ago. At that point in history, major releases of Perl could take many years to come to fruition. To make things more confusing, point releases of a given version sometimes contained large changes (including backwards incompatibilities) that we'd expect in major releases. For example, 5.10.1, released 20 months after 5.10, contained a number of backwards incompatibilities and quite a few new features.