“…[20][21][22][23] With new definitions of fractional derivatives and integrals, 24,25 there has arisen some applications in a few territories of learning. [26][27][28][29][30][31][32] There has gained prominence interest in the investigation of existence and Ulam-Hyers stabilities of differential equations and fractional integrals, be they of the impulsive type, functional or of Volterra. 18,[33][34][35][36] Recently, Sousa et al 37-43 investigated the existence, uniqueness, and stabilities of Ulam-Hyers of fractional differential equations.In this sense, by means of the Ψ-Hilfer fractional derivative, we introduced a class of nonlinear fractional differential equation with the abstract Volterra operator, in order to investigate a new class of Ulam-Hyers stabilities, contributing with new results and consequently for the growth of the area.Consider the fractional differential equation with abstract Volterra operator in a Banach space given by…”