This note provides counterexamples to illustrate that Theorem 4 which is proposed by Cornejo, Lobo and Medina [M. E. Cornejo, D. Lobo, J. Medina, Bipolar fuzzy relation equations systems based on the product t-norm. Mathematical Methods in the Applied Sciences. 2019,42(17):5779-5793] is incorrect. The incorrect of Theorem 4 is due to the inaccuracy of the definition of feasible pair. Then we present the correction of the definition of feasible pair to the contention.