I'm tasking users with a workflow built using SPD2013. Using standard outcomes, Approved and Rejected, I control the flow of subsequent workflow actions. This has worked with relatively few hiccups for about two years.
Recently, the workflow has been suspending after tasking the user with the error:
Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.FormatException: Input string was not in a correct format.
I attempted to create a view for the Workflow Tasks that included the field Task Outcome, but was presented with the following error message:
TypeError: Cannot read property '0' of undefined
TypeError: Cannot read property '0' of undefinedTypeError: Cannot read property '_events' of null
This leads me to believe that the Task Outcome may be set improperly after the OOTB task action has completed, but I cannot seem to understand why. The failure is inconsistent, and occurs after varying tasks within the workflow, or not at all.
Using Fiddler, I examined the contents of a REST call to the task list and found several instances where the TaskOutcome field was null. This corresponds with the error message from the workflow status, and the observed behavior.
The workflow is set to wait for task completion.
Why is the Task Outcome null?