Get Error (error=access_denied) while logging in MVC5 application with facebook SDK - asp.net-mvc

Question

I have developed an application with ASP.NET MVC5. I have used Facebook external authentication in my application.
When I debug this application with the "Locallhost" domain, the Facebook login works well but when I publish the application in the main server,the AuthenticationManager.GetExternalLoginInfo() returns null and it gives me an error like this in the url:
http://xxxxx.com/Account/ExternalLoginCallback?ReturnUrl=%2Fen&error=access_denied#_=_
I have set the "Site URL" as "http://xxxx.com" and "Valid OAuth redirect URIs" as "http://xxxx.com/signin-facebook" in the Facebook development console.
My setting in the Startup.Outh.cs file is:
var FacebookOptions = new Microsoft.Owin.Security.Facebook.FacebookAuthenticationOptions();
FacebookOptions.AppId = ConfigurationManager.AppSettings["Facebook_User_Key"];
FacebookOptions.AppSecret = ConfigurationManager.AppSettings["Facebook_Secret_Key"];
FacebookOptions.Provider = new Microsoft.Owin.Security.Facebook.FacebookAuthenticationProvider()
{
OnAuthenticated = async context =>
{
context.Identity.AddClaim(new System.Security.Claims.Claim("FacebookAccessToken", context.AccessToken));
foreach (var claim in context.User)
{
var claimType = string.Format("urn:facebook:{0}", claim.Key);
string claimValue = claim.Value.ToString();
if (!context.Identity.HasClaim(claimType, claimValue))
context.Identity.AddClaim(new System.Security.Claims.Claim(claimType, claimValue, "XmlSchemaString", "Facebook"));
}
}
};
FacebookOptions.SignInAsAuthenticationType = DefaultAuthenticationTypes.ExternalCookie;
app.UseFacebookAuthentication(FacebookOptions);
I don't know why the external login does not work only in the server with my main domain name. please help me about this problem.

Answer 1

I encountered pretty much the same symptoms you describe:
shortly:
A Facebook authentication worked well on localhost, and after uploading the project to another server (and changing the site URL on Facebook console), authentication did not succeed.
I would recommend you roll back to the MVC template code, and if that works - notice any changes you have made to the middleware code (Startup.Auth.sc).
In particular pay attention to code that interacts with LOCAL configuration, such as Disk I/O and OS permissions for local services.
My particular case:
Starting from the Owin/Katana supported Visual Studio template of a WebAPI project, external login was working perfectly with Facebook, Microsoft and Google OAuth middleware, when testing on localhost.
Later I added come code to Startup.Auth.sc because I needed further authentication activity.
So this was the original code:
public void ConfigureAuth(IAppBuilder app)
{
// see WebAPI template of Visual Studio 2013/2015
...
app.UseFacebookAuthentication(
appId: 99999999,
appSecret: *******);
}
and this was replacement:
public void ConfigureAuth(IAppBuilder app)
{
// see WebAPI template of Visual Studio 2013/2015
...
app.UseFacebookAuthentication(GetFacebookAuth());
}
private FacebookAuthenticationOptions GetFacebookAuth()
{
string picRequest =
String.Format("/me/picture?redirect=false&width={0}&height={0}", ProfileInfoClaimsModel.PIC_SIDE_PX);
var facebookProvider = new FacebookAuthenticationProvider()
{
OnAuthenticated = async (context) =>
{
var client = new FacebookClient(context.AccessToken);
dynamic me = client.Get("/me?fields=id,name,locale");
dynamic mePicture = client.Get(picRequest);
// storing temporary social profile info TO A LOCAL FOLDER
// uploading the local folder to a service WITH A LOCAL CREDENTIAL FILE
...
}
};
var options = new FacebookAuthenticationOptions()
{
AppId = 0123456789,
AppSecret = ******,
Provider = facebookProvider,
};
return options;
}
You may notice that my comments will make the problem obvious - the code points to local resources.
Then I published the project to a virtual server (by Amazon EC2) running Windows Server 2012 with IIS 8.5.
From that moment I kept getting error=access_denied in the redirect from /signin-facebook.
I decided to follow this good old concept, and go back to the original template code. Pretty soon I figured out that I forgot to configure the new server. For instance, the folder the code refers to did not exist and the site had no permission to create it.
Obviously, that solved it.