What does the "EXDEV: cross-device link not permitted" error mean? : <p>What does this error actually mean? What is a "cross-device link"?</p>

<p>It is mentioned on <a href="http://docs.libuv.org/en/v1.x/errors.html" rel="noreferrer">this libuv page</a> but it doesn't give any details beyond "cross-device link not permitted".</p>
