If there are multiple instances of the same receive task waiting for a signal and you call this task from Camel e.g. like this:
Activiti throws the following exception:
To my understanding this happens because Activiti does not know which receive task instance I'm calling from Camel when there's multiple instances.
In the forums user trademak suggested adding an execution id to Camel exchange which could be used for signaling the correct receive task instance.