Paypal Error Message: You must specify only one primary receiver and at least one secondary receiver

If you come across this error, “Error Message: You must specify only one primary receiver and at least one secondary receiver,” that looks like this on a PayKickstart checkout page:

Confirm that the PayPal account being used to process transactions in PayKickstart is NOT the same PayPal account used in the My Profile section for one of the Partners.

PayPal cannot send commission payouts to the same account/itself.