Cardinal Brandmüller has contradicted Bishop Schneider's thesis that there have been errors in councils which later needed to be corrected.
Regarding the Council of Constance (1415-1418) which professed the heresy that a council is above the pope (conciliarism), Brandmüller told Sandro Magister (July 13) that the assembly issuing those decrees didn't constitute a legitimate Ecumenical Council because they were following Anti-Pope John XXIII (+1419).
Only the second part of this Council which proclaimed Martin V as the legitimate pope, is considered to be canonical. Martin V approved all conciliar documents, except those on conciliarism.
Regarding the Council of Florence (1439-1445), Brandmüller admits that it defined that a valid priestly ordination requires the conferral of the instruments of the office (chalice and paten) and that Pius XII established 1947 that this would in future no longer be necessary by declaring that the matter of the sacrament is only the imposition of hands …More