Why is my workflow failing to send a second email?

Question

I made an approval workflow in SP Designer 2013 for my custom list on a 2013 site.

My workflow waits for the column "submit for approval?" to equal yes then it sends an email to the approver. Then it waits for the column "Approved?" to equal yes then it is supposed to send an email to the creator saying that it has been approved. For some reason the second email never sends and the workflow becomes suspended.

I get this long error message,

RequestorId: 06262505-fdc3-c27e-0000-000000000000. Details: An unhandled exception occurred during the execution of the workflow instance. Exception details: System.ArgumentNullException: Value cannot be null. Parameter name: Input 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)

Any ideas on why this is happening?

Answer 1

I was never able to get this to work with 1 workflow but I did find a work around by making a second workflow. I placed the second half of my workflow (the half that was failing) and put it on a second workflow by itself and everything works the way it is supposed to.