I sent over a link via private message. I'd love to take a look at your working file, the camel one, if that's all right? I want to make sure I'm setting things like the bone weights up correctly when the bones are actually deforming the mesh. I'm still pretty new at this!
In another thread, it was mentioned that someone solved this because their armature had multiple root bones. I noticed I had two, but after I parented the head to the body, I still got the same error. Still, it was a fix for them and I figured I'd mention it.
I think this might be a sort of catchall error message for more unusual situations.
I thought mine might be erroring out because I had combined multiple meshes into the same object, so I tried separating them out (they showed that could be done during the pirate part of the livestream last week, just need 6 LODs for each object). I still got the error, though. I'm going to try starting from a completely fresh blend file, pasting each mesh in, and just rebuilding piece by piece until I can spot what errors out. Frustrating, but I'm sure they're working to figure it out!