There are some BPEL activities that cannot be used as the target of a catch or catch all boundary event.

You cannot add a compensate, compensate scope, or rethrow activity as a linked target of a catch or catch all. The catch and catch all events are interrupting events, triggered by the termination of the scope they are attached to. As such, they get executed outside of the scope. The work of the compensate, compensate scope, and rethrow activities is to execute within a scope. These activities must be added inside a scope's catch or catch all handler.