I'm in the Workflow Health page, and I see I have several workflow instances suspended with the following error:

An unhandled exception occurred during the execution of the workflow instance. 
Exception details: System.InvalidCastException: The value 'd/results(0)/Assign_x0020_ToId' 
cannot be read as type 'String'

I tried resuming them all by clicking "Resume all" from the dialog box, but they are still stuck as "Suspended". Any help will be greatly appreaciated.

Thank you!

1 Answer 1


This may occur if you are using an action (like start task or whatever) at your workflow that return the Assigned To field with default string selection.

So try to review your workflow and make sure you the return field Assigned To as your requirement as shown below in the drop-down list of Return field as

enter image description here

  • I reviewed all my return fields on Designer and reverted all back from String, and I am still getting instances of workflows suspended.
    – Ivan
    Sep 23, 2016 at 15:19
  • is it suspended with the same error ? Sep 23, 2016 at 15:43
  • Yes. Suspended with the same error. I double checked in Designer and InfoPath to make sure the return type for this field is not a string.
    – Ivan
    Sep 23, 2016 at 16:09
  • Would it help if I enable "activate workflow manually" in Designer? Right now now, it is set up to fire up the workflow if a list item is created or changed.
    – Ivan
    Sep 23, 2016 at 19:05
  • I think this is not related to your issue , this options to when to start your workflow Sep 23, 2016 at 20:22

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