A method for protecting a unit for converting a web substrate to limit a jam of the substrate inside the unit, the unit converting the substrate when the unit is stopped, in a packaging production machine: the steps of: detecting at the outlet of the unit that the converted web does not come out; stopping a motor of an infeed arrangement to prevent the substrate from entering the unit; stopping a motor of a feathering drive; and simultaneously stopping the machine, and guiding the substrate to an accumulation storage.