When loading AoP 2.0.4, I encountered this error:
Failed to load mods: Cycle in technology tree detected.
planet-discovery-corrundum
-> electrochemical-science-pack
-> aop-arc-furnace
-> big-mining-drill
-> tungsten-steel
-> metallurgic-science-pack
-> planet-discovery-corrundum
I've briefly checked the codes but I didn't see why would this happen.