Call to IdentityServer4 generates System.NullReferenceException: Object reference not set to an instance of an object

Question

I am intending to get a bearer token via IdentityServer4 via my web project, and I am getting this exception. The exception is in the IdentityServer4 open source class library. The field url is null, and this causes the NullReference exception in the AddQueryString method, see https://github.com/IdentityServer/IdentityServer4/blob/master/src/Extensions/StringsExtensions.cs

The log files show;

IdentityServer4.Endpoints.AuthorizeEndpoint:Information: ValidatedAuthorizeRequest { "ClientId": "SIR", "ClientName": "SIR", "RedirectUri": "http://localhost:53200/signin-oidc", "AllowedRedirectUris": [ "https://localhost:44314", "http://localhost:53200/signin-oidc" ], "SubjectId": "anonymous", "ResponseType": "code id_token", "ResponseMode": "form_post", "GrantType": "hybrid", "RequestedScopes": "openid profile", "State": "OpenIdConnect.AuthenticationProperties=WBfqf-a6W0K-0x6giakJP1GCkjUyG0wzOgAr9AuitPNyUb6wsIlzJN-Yvv-ARRdTd5huJIIl3N0mpI95EbLzGKIVmAhXr4JiIWKo2dOCTFI7PH218T9V1vVkKP3kFmQgtRRYRagG9YEA2PvyMtxzQXMf4v3pPequ8Am7H_8TIfgMqspxAnTsXQ4K-cD_TBTVFc45AiDiylpWup1_Ovrpqu700JCGimHZJRuXP25MHMs", "Nonce": "636809130138863279.M2IyNTYyZTgtZTk0Ni00OWU5LWI4MmMtNGU2MWY4M2FkMzQzNzExYjRjYjYtOWY4MC00NjQwLWEyZGYtYzgzYjljZTY4ZDFj", "Raw": { "client_id": "SIR", "redirect_uri": "http://localhost:53200/signin-oidc", "response_mode": "form_post", "response_type": "id_token code", "scope": "openid profile", "state": "OpenIdConnect.AuthenticationProperties=WBfqf-a6W0K-0x6giakJP1GCkjUyG0wzOgAr9AuitPNyUb6wsIlzJN-Yvv-ARRdTd5huJIIl3N0mpI95EbLzGKIVmAhXr4JiIWKo2dOCTFI7PH218T9V1vVkKP3kFmQgtRRYRagG9YEA2PvyMtxzQXMf4v3pPequ8Am7H_8TIfgMqspxAnTsXQ4K-cD_TBTVFc45AiDiylpWup1_Ovrpqu700JCGimHZJRuXP25MHMs", "nonce": "636809130138863279.M2IyNTYyZTgtZTk0Ni00OWU5LWI4MmMtNGU2MWY4M2FkMzQzNzExYjRjYjYtOWY4MC00NjQwLWEyZGYtYzgzYjljZTY4ZDFj", "x-client-SKU": "ID_NET461", "x-client-ver": "5.3.0.0" } } IdentityServer4.ResponseHandling.AuthorizeInteractionResponseGenerator:Information: Showing login: User is not authenticated IdentityServer4.ResponseHandling.AuthorizeInteractionResponseGenerator:Information: Showing login: User is not authenticated IdentityServer4.ResponseHandling.AuthorizeInteractionResponseGenerator:Information: Showing login: User is not authenticated IdentityServer4.ResponseHandling.AuthorizeInteractionResponseGenerator:Information: Showing login: User is not authenticated Exception thrown: 'System.NullReferenceException' in IdentityServer4.dll Exception thrown: 'System.NullReferenceException' in IdentityServer4.dll 'dotnet.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.1.6\System.Diagnostics.StackTrace.dll'. Symbols loaded. 'dotnet.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.1.6\System.Reflection.Metadata.dll'. Symbols loaded. 'dotnet.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\2.1.6\System.IO.MemoryMappedFiles.dll'. Symbols loaded. IdentityServer4.Hosting.IdentityServerMiddleware:Critical: Unhandled exception: Object reference not set to an instance of an object.

System.NullReferenceException: Object reference not set to an instance of an object. at IdentityServer4.Extensions.StringExtensions.AddQueryString(String url, String query) in C:\local\identity\server4\IdentityServer4\src\Extensions\StringsExtensions.cs:line 197 at IdentityServer4.Endpoints.Results.LoginPageResult.ExecuteAsync(HttpContext context) in C:\local\identity\server4\IdentityServer4\src\Endpoints\Results\LoginPageResult.cs:line 61 at IdentityServer4.Hosting.IdentityServerMiddleware.Invoke(HttpContext context, IEndpointRouter router, IUserSession session, IEventService events) in C:\local\identity\server4\IdentityServer4\src\Hosting\IdentityServerMiddleware.cs:line 59 IdentityServer4.Hosting.IdentityServerMiddleware:Critical: Unhandled exception: Object reference not set to an instance of an object.

So in the AddQueryString method, the url is null. In my web client my startup method is;

public void Configuration(IAppBuilder app)
{
    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AuthenticationType = Settings.SignInAsAuthenticationType    // "Cookies";
    });

    app.UseOpenIdConnectAuthentication(openIdConnectOptions: new OpenIdConnectAuthenticationOptions
    {
        AuthenticationType = "oidc",
        Authority = Settings.AuthorityUrl,      //ID Server,  "https://localhost:44314/"; https://localhost:44307/
        ClientId = Settings.ClientId,           // "SIR"
        Scope = Settings.Scope,                 // "openid profile";
        ResponseType = Settings.ResponseType,   // "id_token code";
        SignInAsAuthenticationType = Settings.SignInAsAuthenticationType,
        //--------------------------------------// "Cookies";
        RedirectUri = Settings.RedirectUri,     // URL of website, http://localhost:53200/signin-oidc;
        RequireHttpsMetadata = Settings.RequireHttpsMetadata,
        //--------------------------------------// true
        ClientSecret = "secret"
    });

    app.Use(async (ctx, next) =>
    {
        var message = ctx.Authentication.User.Identity.IsAuthenticated
            ? $"User: {ctx.Authentication.User.Identity.Name}"
            : "User Not Authenticated";
        await next();
    });
}

Notice that I am using Microsoft.Owin

The client in my IdentityServer4 is;

public static IEnumerable<Client> Clients()
{
    return new[]
    {
        new Client
        {
            ClientId = "SIR",
            ClientName = "SIR",
            AllowedGrantTypes = GrantTypes.Hybrid,
            AllowedScopes = new[]
            {
                IdentityServerConstants.StandardScopes.OpenId,
                IdentityServerConstants.StandardScopes.Profile
            },
            RedirectUris = {
                "https://localhost:44314",
                "http://localhost:53200/signin-oidc"
            },
            ClientSecrets = { new Secret("secret".Sha256())}
        }
    };
}

Why is this and how do I fix this?

Possible duplicate of What is a NullReferenceException, and how do I fix it? — Symon
Are you able to share the code that is causing this? What line of code is it? Obviously something is null and must be given value. — Symon
The error is in the IdentityServer4 code, which is an open source library. If you are familiar with the library the error is caused by the url field being null in the AddQueryString method. I want to know why this field is null. — arame3333
This is not a duplication question about NullReferenceException. This is a question about how to use the IdentityServer4 open source library which is why I have tagged it in the question. — arame3333

Berlstone Berlstone · Accepted Answer · 2019-10-22T22:03:24

Add UserInteractionURL to AddIdentityServer. It will fix your problem

 services.AddIdentityServer(options =>
                {
                    options.UserInteraction = new UserInteractionOptions()
                    {
                        LogoutUrl = "/Identity/account/logout",
                        LoginUrl = "/Identity/account/login",
                        LoginReturnUrlParameter = "returnUrl"
                    };
                })

Call to IdentityServer4 generates System.NullReferenceException: Object reference not set to an instance of an object

1 Answers