JsonUtility gives "name == NULL" error messages

I'm trying to serialize this json string using the new JsonUtility

 {"playerFollowWeight": "0.503937", "blocks": [{"id":2,"pos":[4,0,0]},{"id":1,"pos":[-4,0,0]}], "camYStart": "0.0", "requiredTime": "5.372032", "orderIndex": 1.0, "camZoomStart": "2.79273199573", "camXStart": "0.0"}

Into the type LevelData

 [Serializable]
 public class LevelData{
   public Dictionary<string,Dictionary<string,object>> levelBlocks = new Dictionary<string,Dictionary<string,object>>();
   public string name = "";
   public float playerFollowWeight = 0.5f;
   public float hue = 3.583333f;
   public float requiredTime = 10f;
   public float camZoomStart = 3.16f;
   public float camXStart = 10f;
   public float camYStart = -9f;
   public float ownerFinishTime = 0f;
   public bool finishedByOwner = true;
   public Vector3 customCenter;
   public BlockData[] blocks;
 
   public LevelData(){}
 }
 
 [Serializable]
 public class BlockData{
   public int id = 0;
   public Vector3 pos;
   public BlockData(){}
 }

and I'm getting tons of name == NULL errors. Does anyone know what's causing this? I'm pretty sure it has something to do with the blocks array. But I can't seem to figure out what exactly is causing this.

Edit: it turns out Vector3 doesn't work with [4,0,0], you have to actually give each component a name: {"x":4,"y":0,"z":0} Using it the other way does actually work, it just gives an error message also.