Latest version of Robot256Lib will do a better job of preserving schedules and interrupts when MUTC replaces locomotives, thanks to the new schedule API in 2.0.38. Please update Factorio and Robot256Lib!

The mod Multiple Unit Train Control (1.0.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event MultipleUnitTrainControl::on_tick (ID 0)
Robot256Lib/script/carriage_replacement.lua:295: attempt to index field 'schedule' (a nil value)
stack traceback:
Robot256Lib/script/carriage_replacement.lua:295: in function 'replaceCarriage'
MultipleUnitTrainControl/control.lua:164: in function 'ProcessReplacement'
MultipleUnitTrainControl/control.lua:275: in function 'ProcessTrain'
MultipleUnitTrainControl/control.lua:377: in function 'ProcessTrainQueue'
MultipleUnitTrainControl/control.lua:405: in function <MultipleUnitTrainControl/control.lua:402>

using your library up to date V2.0.9
happens when placing a train all premade trains are working fine

Thanks for the report. Should be fixed in Robot256Lib 2.0.10.

tested and works now, Im assuming from the above it was because of no schedule?