When did the League of nations require unanimous voting?

The League of Nations required unanimous voting for key decisions, particularly in matters of important issues such as amendments to the Covenant, admission of new members, and decisions concerning disputes between member states. This requirement was established in the League's Covenant, which was adopted in 1919. The need for unanimity often led to challenges in decision-making, as it allowed any single member to block resolutions, contributing to the League's eventual ineffectiveness.