When using the web service interface you try to set an Incident to 'Waiting for Customer' but get an error message:
Unhandled system exception: Exception of type 'DataLayer.PromptException' was thrown.
The web service is trying to set an Incident to 'Waiting for Customer' status when the error is presented.
If you do the same thing through the UI a prompt appears.
This is caused by the Trigger Rule 'StopEscalationClock'.
This rule has an action to add a Journal entry, prompting the user to enter a note:
You will need to adjust this rule so that it does not prompt the web service. You could do this by excluding that specific user role, e.g. change:
$(Prompt("Enter Notes for Customer", ""))
$(iif(CurrentUserRole() == 'API_Role',
"Incident set to Waiting for Customer by Web Service Interface",
Prompt("Enter Notes for Customer", ""))
Adjust the role and text to suit.