This has been pestering me for some time now, there is no apparent error (which I see) in these models, no circular reference however after rendering the first few uvs I get the “Circular Reference in Texture stack” error, it’s really annoying me right now, any help please? 
Tech Demo.blend (753 KB)
and before someone posts a link to another one of the same question, I have looked around, I don’t see the same issue here so please check the file once.
Yeah, don’t put the finished baked texture into the texture stack of the material yet. Save the image, but keep it in your directory waiting until you finish making your bakes - the circular reference is because you are baking to a texture in your material OF your material. Simply load a new image in the editor, enter edit mode so the UVs appear over the image, and then bake your pass - then save to your image name in directory.
Also, there were no images in the file since you didn’t pack them, but the name of the texture in your material texture stack tipped me off.