Problem UpdateProcessInstanceData c#

I am developing a small utility in C # which allows us to update the DATA in relation to a request.
So I use RuntimeService.
I managed to read the process list, the request list and the request data.
However, I cannot update the request data. I’m using UpdateProcessInstanceData
I give you my code so that you can give me your opinion.

On the click of the button, I create my xml file with the value to modify and I get the idProcess.
I run this function


I tried this method


And I tried this one. The same error appears.


Is this a problem when creating my xml ?? Here’s how it is!

I really don’t see where the error can come from !!


Are you able to connect to the webservice page?

If so, does is work when you try your query directly in the webservice?


Thank you for your return but I had already looked at these links.
I can’t even get this command to work through this interface.

In workflowcontext I put this value

I do not know what to do, I looked in the doc and I do not have the impression of false data. Please help me !

Something seems not setup properly.

Go to the server that hosts the application.
Open the Event Viewer application then navigate to Windows Logs -> Application.

500 errors usually get logged here and you can see more details regarding the cause of this issue.

I have no error message on the server. I really don’t see how to fix my problem.
Do you have any other solution for my problem ??

Best option is to open a ticket on the support helpdesk site so that the WorkflowGen team can investigate your issue.