Scenario:
Error while transferring data from Web TimeSheet to QuickBooks says "Payroll Item is blank in Web TimeSheet". User was trying to integrate Web TimeSheet with QuickBooks and got an error saying "Payroll Item blank in Web TimeSheet". But there is no default field called Payroll in Web TimeSheet.
 
Resolution:
User had created a User Defined Field in Project Level by the name "Payroll". This field was a required field and hence if left blank the integration was failing. When this field was populated with a valid report the integration completed successfully.