Reported by @apaseall on the forum.

This mod interacts with ExtraPlanetaryLaunchPads in so much that a reference is made to Productivity Factor.

Please update this reference to reflect that ExtraPlanetaryLaunchPads fairly recently went through a name change for its modules.

Specifically MODULE ExWorkshop is now called ELWorkshop.

Confirmed, ExtraPlanetaryWorkshops performed a save-breaking update in their 6.0 release and renamed modules.

Reference: https://forum.kerbalspaceprogram.com/index.php?/topic/54284-144-extraplanetary-launchpads-v610/&do=findComment&comment=3347604