As per Bob's changelog:
Version: 0.17.3
Date: 29. 03. 2019
Bugfixes:
- Renamed battery-equipment technologies to bob-battery-equipment to fix the Factorio 0.17.23 non-contiguous technology name issue.
- Renamed energy-shield-equipment technologies to bob-energy-shield-equipment to fix the Factorio 0.17.23 non-contiguous technology name issue.
Renaming energy-shield-equipment-6 to bob-energy-shield-equipment-6 in the file data-updates.lua fixes properly.
Basically line 6 reads:
data.raw["technology"]["PaA-mk4-power-armor"].prerequisites={"PaA-mk3-power-armor", "fusion-reactor-equipment-4", "energy-shield-equipment-6"}
and should read:
data.raw["technology"]["PaA-mk4-power-armor"].prerequisites={"PaA-mk3-power-armor", "fusion-reactor-equipment-4", "bob-energy-shield-equipment-6"}