Path substitution

I wanted to sync favorites on my PC and my TV box. So I did like

Code:
<substitute>
    <from>special://profile/favourites.xml</from>
    <to>ftp://user:[email protected]/kodi/favourites.xml</to>
  </substitute>

Now, what interests me is what happens when my server is down? Does it cache a version of favorites.xml so it is displayed or displays nothing?