Hi Kris,
thanks for your answer, you are probably right. Yesterday I tested the whole day, using the registered users john,mary and krisv and the error has not occured. Last week I tried with "michael" without registering. But I was able to create a task with the non existing user. Would be nice to have an error message if a user does not exists. This is no complaint. It is a great project and I'm looking forward to understand everything.
Perhaps such a message would make no sense since it can happen that users will be registered after a process is defined?
Great manual, too.
Michael