When I try reassigning the task to a different SharePoint workflow, it gets suspended with following error message:

Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.FormatException: Input string was not in a correct format. at Microsoft.Activities.Hosting.Runtime.Subroutine.SubroutineChild.Execute(CodeActivityContext context) at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager) at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation)

Do you know why this happens?

2 Answers 2


As mentioned in the error message, issue is an input string is not being in a correct format. Assuming that you are assigning task to another user (not to another workflow as in the question), issue might be the way how the AssignedTo field is populated. Try to use UserID, instead of Display Name.


I had a team site (no publishing feature) in test environment where the workflow was working correctly and tasks could be re-assigned. Created a site in production that had the publishing feature enabled for the branding and just used the Workflow Tasks list that come with that feature with my task content types added. Workflow kept suspending when tasks were re-assigned. Created a new task list in for the workflow in SharePoint Designer, added my task content types and all working correctly now.

I believe the problem for me was using the Workflow Tasks list that comes with the publishing feature rather than creating a task list specifically for the workflow.

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