This corrigendum provides a variant of the Brondsted-Rockafellar theorem, which helps to correct an error in the proof of the sufficiency part of Theorem 2.8 in [X. Y. Zheng, SIAM J. Optim., 33 (2023), pp. 338-359] and to establish the correct characterization for a closed convex set to be C-p-differentiable. In particular, in the original paper, Theorem 2.8 holds with p/epsilon(1)+p replacing epsilon(p/2) and Theorem 3.2 holds with "1+p/p-order-well-posed solvable" replacing "2/p-order-well-posed solvable." All other results remain true.