Error 1530: UPN invalid (characters 2-4 not a recognised LA code).

To check the pupil UPN, go to the student profile. In the extended tab, under the school information heading, check the UPN.

This error means that characters 2-4 of the UPN are incorrect. If the pupil is new to your school you may need to confirm with the previous school if you believe this number to be correct.  

You can find more information on UPNs from the DfE guidance found here.