I just moved EliMZ Book above ARPG Core and everything worked.
In fact, another error pops up, but on the EliMZ_CharacterManager. The problem is the same, and I believe it can also have the same solution as we discussed on this topic:
Okay. Gonna try to swap them and see what I get. The only problem I have is that I have no idea how to get in touch with ARPG author(s) to let them know about possible incompatibilities, but well... My choice, my problem. Thank you again for your time!
Well I feel so stupid now.... I've moved it up like you said and now it works. I was almost sure that it didn't worked before no matter where @_@ So sorry for troubling you with no reason. I'm so happy it works!!!