I'm performing a SQL query through hibernate, which looks like: SELECT thi FROM track_history_items thi JOIN artists art ON thi.artist_id = art.id WHERE thi.type = "TrackBroadcast" GROUP BY art.name ORDER thi.createdAt DESC but I'm getting the message that 'Node to traverse cannot be null!'. Anyone know what could be causing this? --EDIT-- I'm pretty sure that this problem is being caused by the possibility of artist_id to be null. However, I can't prevent this, so can I just skip the rows track_history_item rows which have a null artist_id?