IdentityServer "invalid_client" error always returned : <p>I'm trying to use IdentityServer3, but don't know why I'm getting "invalid_client" error always, always no matter what I do.</p>

<p>This is the code I'm using:</p>

<pre><code>//Startup.cs (Auth c# project)
public void Configuration(IAppBuilder app) {
    var inMemoryManager = new InMemoryManager();
    var factory = new IdentityServerServiceFactory()
        .UseInMemoryClients(inMemoryManager.GetClients())
        .UseInMemoryScopes(inMemoryManager.GetScopes())
        .UseInMemoryUsers(inMemoryManager.GetUsers());

    var options = new IdentityServerOptions {
        Factory = factory,
        RequireSsl = false
    };

    app.UseIdentityServer(options);
}
</code></pre>

<p>InMemoryManager helper.</p>

<pre><code>//InMemoryManager.cs
public class InMemoryManager {
    public List&lt;InMemoryUser&gt; GetUsers() {
        return new List&lt;InMemoryUser&gt; {
            new InMemoryUser {
                Username = "alice",
                Password = "password",
                Subject = "2",
                Claims = new [] {
                    new Claim("User name", "Alice")
                }
            }
        };
    }

    public IEnumerable&lt;Scope&gt; GetScopes() {
        return new[] {
            new Scope {
                Name = "api1",
                DisplayName = "API 1"
            }
        };
    }

    public IEnumerable&lt;Client&gt; GetClients() {
        return new[] {
            new Client {
                ClientName = "Silicon on behalf of Carbon Client",
                ClientId = "carbon",
                Enabled = true,
                //AccessTokenType = AccessTokenType.Reference,

                Flow = Flows.ResourceOwner,

                ClientSecrets = new List&lt;Secret&gt; {
                    new Secret("secret".Sha256())
                },

                AllowedScopes = new List&lt;string&gt; {
                    "api1"
                }
            }
        };
    }
}
</code></pre>

<p>This is the result I always get.</p>

<p><a href="https://i.stack.imgur.com/sBrOW.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sBrOW.png" alt="Postman error"></a></p>

<p>I'm using postman to try the Auth Server, but I always get that error. I've read another solutions but none seeme to works, I don't know what else to try.</p>

<p>Cheers.</p>
