The On Process Start action is a process callback action that allows you to implement business rules to validate whether a launched process instance can start the execution. If you want to stop the process from beginning the execution, raise an exception using the Raise Error element. Learn more about how to Explicitly Raise an Exception.
An On Process Start action can have local variables.
Process Callback Actions | Process Activities Callback Actions | Process Activities Life Cycle | Explicitly Raise an Exception | Designing Actions | Designing Processes | Process Flow Toolbox