I understand that there are no other consists. BUT is there a Service (Particularly one of the other 3 with "UP" in their name.) which has a TrainCfg line that looks like this:
TrainCfg ( UPSP 175 + 2 lds dpu ) instead of TrainCfg ( "UPSP 175 + 2 lds dpu" )
That will cause an Error of UPSP.con is missing.