Hi,
What do you mean by “trying to create a process task”? Normally you don’t have to create the ProcTask entity manually. It will be created automatically. I’ve already mentioned it in this topic: [url=https://www.cuba-platform.com/discuss/t/bpm-issue]https://www.cuba-platform.com/discuss/t/bpm-issue[/url].
I can’t say anything about the error based on the information you provided. Can you please attach a small demo project that reproduces your issue.