Contradiction with 2 Kings 23:29-30
These verses explain that Josiah was killed in battle at Megiddo, which challenges the notion that he would die in peace.
2 Kings 23:29-30: In his days Pharaohnechoh king of Egypt went up against the king of Assyria to the river Euphrates: and king Josiah went against him; and he slew him at Megiddo, when he had seen him.
Contradiction with 2 Chronicles 35:22-24
These verses describe Josiah's death in battle against Pharaoh Necho, suggesting that his end was not peaceful despite the prophecy.
2 Chronicles 35:22-24: Nevertheless Josiah would not turn his face from him, but disguised himself, that he might fight with him, and hearkened not unto the words of Necho from the mouth of God, and came to fight in the valley of Megiddo.