Invalid redirect_uri with 'omniauth-facebook' gem

Question

So I went to this guide that explains how to start with omniauth. When I got to the end of step 4 to test the application at localhost:3000/auth/facebook, I got this error:

{ 
    "error": {
        "message": "Invalid redirect_uri: Given URL is not allowed by the application configuration.",
        "type": "OAuthException",
        "code": 191
    }
}  

I understand the problem is the URL in the Facebook developer center, but none of the solutions I read works for me...

(I know that there are some questions before regarding this issue, but I'm new to Ruby on Rails and need an explanation for dummies.)

Answer 1

Defining these settings at the Facebook developer center solved this for me:

• App Domain: (blank)

• Site URL: http://localhost:3000

Answer 2

Check the website option and set the site URL to http://localhost:3000/.