How to complete a task using REST API (Activiti 5.15)

[jy104]

Hi everybody,
I created a process in Activiti 5.10 which contains only one Human task.
so far every thing is alright using REST, I can deploy, undeploy and fire process via REST Client.
but when I tried to complete task using REST, I always got the following error message:
{"errorMessage":"The server encountered an unexpected condition which prevented it from fulfilling the request","statusCode":500}

as per User guide, I tried new REST API and Legacy API as well, all failed.
appreciate for help

[martin_grofcik]

Hi,

I had not issue to complete user task through REST api on 5.15.1.

Regards
Martin