An Exception Transition is used to submit the instance to an Exception Handler flow when the flow object or group of activities fail or throw an exception.
After you create the transition, a line with a directional arrow connects the two flow objects on the design workspace.
The source of the transition is the flow object or group where the exception occurred, and the target is the first flow object in the exception handler flow. As the exception handler flow is independent from the main process flow, it cannot have transitions back to the main process flow.
Exception holder variable: you can create and define an instance variable as the Exception holder variable. If you do not define one, Studio creates it automatically.
Once the exception occurs it is stored in this variable and it is available within the exception flow that is handling the exception. It can be used by the developer to debug or analyze the exception in depth.
You can create only one variable and re-use it in all the exception transitions or you can associate different instance variables to each exception flow. Normally the variable type matches the exception type.
If there is no variable defined (backward compatibility), a default exceptionHandler instance variable (Any type) is created when you check the design.
At runtime if the variable receives an unmatching type, then a warning is logged.
The variable content is available only within the Exception flow to where the instance is routed through the exception transition. Therefore the exception contained in the variable is not propagated to other processes.