Divine Mercy Sunday said to be the same as Second Sunday of Easter
Vatican approval
The devotion was actively promoted by Pope John Paul II. On April 30, 2000, the  Canonization of Faustina Kowalska took place and the second Sunday of Easter was officially designated as the Sunday of the Divine Mercy (Dominica II Paschae seu de divina misericordia) in the General Roman Calendar. On April 22, 2001, which was one year after establishing Divine Mercy Sunday, Pope John Paul II re-emphasized its message in the resurrection context of Easter: