Problem: According to 2 Chronicles 21:16–17, Jehoram’s sons were only taken captive by the Philistines and the Arabians. By contrast, this passage says they “killed all the older sons.”
Solution: There is no contradiction here for two reasons. First, it was only the “older” sons who were killed, not all of them. The others could have been taken captive. Second, they could have first taken them captive and then afterward killed them.