Unable to get access token from Facebook. Got an OAuthException says “Error validating verification code”
I recently dealt with exactly this problem: everything matched, but it failed with the OAuthException. The thing that made it work was to change the redirect uri (in both requests for the flow) from: http://foo.example.com to http://foo.example.com/ I.e., add the trailing slash. And then it worked. Stupid and silly, but there you go.