Error message

SPAWN/SUBMIT is blocking the context change

Cause of error

The PLC in-code tracer cannot be started because one of the SPAWN/SUBMIT jobs in the system blocked all context switching for more than 3 seconds.

Error correction

Every program loop in a SPAWN/SUBMIT job must contain an opportunity to switch contexts (cooperative multitasking). You can do this by calling one of the PLC modules 9260, 9262, 9263, 9212, 9216, 9217, 9108 or 9109.
You can find the faulty SPAWN/SUBMIT job on the process monitor because it stays the "RUN+" state for a long time.