Your code looks good. It could be something to do with the arguments you're passing to create, since the description for ERR_INVALID_ARGS reads: "Body is not properly described or name was not provided." Are you sure your name is a string? And if you console.log your BODY, it's an array of parts (numbers)? The only other thing I can think of is that maybe you're passing in too much energy and it's trying to create too many parts, but I haven't personally tested whether you get that error code when trying to create a creep with parts that exceed your energy. Long story short, I don't see any problems, it must have to do with the way you're calling it.