Zedekiah was 21 years old when he became king; he reigned 11 years in Jerusalem.
References for 2 Chronicles 36:11
He did what was evil in the sight of the Lord his God and did not humble himself before Jeremiah the prophet at the Lord's command.
He also rebelled against King Nebuchadnezzar who had made him swear allegiance by God. He became obstinate and hardened his heart against returning to the Lord God of Israel.
References for 2 Chronicles 36:13
All the leaders of the priests and the people multiplied their unfaithful deeds, imitating all the detestable practices of the nations, and they defiled the Lord's temple that He had consecrated in Jerusalem.