This used to work so I'm not sure what went wrong. User is able to login to Facebook just fine. Logging out is the problem.
I log the user out by redirecting them to the Facebook logout php script. $facebook->getLogoutUrl();
When the user clicks on that link, they are logged out of the Facebook page. However, when they are directed back to my site, I notice the fb_ cookie is still there. PHP SDK still returns the user fb session details. The strange thing is going to www.facebook.com shows I'm already logged out of Facebook.
What could be going wrong here? Thanks, I'm stumped :(.
Okay, in the end, what I did was generate a getLogoutUrl() with a next= address url to my logout script which will remove the facebook cookie by setSession(null).
来源：https://stackoverflow.com/questions/3385499/facebook-oauth2-logout-does-not-remove-fb-cookie