This error arises when there is Post Looked After information on the student's profile, but no entry for Early Years Pupil Premium.
To check this you would go to the student profile and their Extended Tab. If you scroll down to the Support Information section, you will find they have post-looked after arrangements entered (no longer In Care).
If this is accurate, you will need to enter a Early Years Pupil Premium category in the Further Information section of the Extended Tab.
Here are the available categories for the funding: