This error occurs when a Pupil has Free School Meals showing in their Extended tab of their Profile, under Further Information, but no start date.
Click on the Manage Tab beside 'is ..... eligible for free meals?'
When entering a period of Free School Meals and not a date, you will see the following -
'FSM would not be expected to have an end date'
Please click on the Ok and enter the valid from date using the calendar.