title: Changing domain for Facebook App
body: <p>I have a site which allows users to register by Facebook. Associated Facebook application is assigned to the domain, for example, www.abcd.cl. At present, there are a lot of registered users. Besides that domain, if users connect using other domain, for example, www.efgh.cl, they will be redirected to the main domain www.abcd.cl.</p>
  
  <p>Well... customer needs now that the main domain to be www.efgh.cl and the secondary www.abcd.cl. So, if someone enters in www.abcd.cl, he will be redirected to www.efgh.cl.</p>
  
  <p>The question is, after I change all DNS matters, can I just change the domain in Facebook App? what about current registered users?</p>
  
  <p>I have this question because when the site was under development, we used the URL dev.abcd.cl. I registered with my facebook account at that time. When we passed to production, URL changed to www.abcd.cl. From that time on, I cannot log in using Facebook. I receive the error: "user already registered".</p>