Why did the u. S. Senate refuse to ratify the treaty of versailles after world war i?

In 1919 the Senate rejected the Treaty of Versailles, which formally ended World War I, in part because President Woodrow Wilson had failed to take senators' objections to the agreement into consideration. They have made the French treaty subject to the authority of the League, which is not to be tolerated.

the Treaty of Versailles based primarily on objections to the League of Nations. The U. S. would never ratify the treaty or join the League of Nations.