Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
You asked a process to do something, and the action you named is not one the lifecycle knows. A process can be asked for exactly five things: reboot, stop, kill, vanish, and resurrect. Each one has a precise effect on the walk and on the process itself, written down in gtr.feml. The process row checks your word against that list, by plain lookup. If the word is not there, or if you gave no action at all, the engine refuses. It does not turn the unknown word into a harmless do nothing, and it does not guess that you meant the nearest spelling. Either of those would hide your mistake. Both ways of writing the call, process with the action as an argument, or process dot the action, land on this same refusal. The message shows the word you wrote, or none, and the full list of declared actions. So the fix is right there on your screen: pick one of the five words, and the lifecycle will do exactly what that word promises.
Text from the Rush engine's error catalogue.