InvalidOperationException: Sequence contains no elements

[SachinSaxena]

InvalidOperationException: Sequence contains no elements System.Linq.ThrowHelper.ThrowNoElementsException() System.Linq.Enumerable.Single(IEnumerable source) Sustainsys.Saml2.IdentityProvider.ReadMetadataIdpDescriptor(EntityDescriptor metadata) Sustainsys.Saml2.IdentityProvider.ReadMetadata(EntityDescriptor metadata) Sustainsys.Saml2.IdentityProvider.DoLoadMetadata() Sustainsys.Saml2.IdentityProvider.ReloadMetadataIfRequired() Sustainsys.Saml2.IdentityProvider.get_SingleSignOnServiceUrl() Sustainsys.Saml2.IdentityProvider.CreateAuthenticateRequest(Saml2Urls saml2Urls) Sustainsys.Saml2.WebSso.SignInCommand.InitiateLoginToIdp(IOptions options, IDictionary<string, string> relayData, Saml2Urls urls, IdentityProvider idp, Uri returnUrl, HttpRequestData request) Sustainsys.Saml2.WebSso.SignInCommand.Run(EntityId idpEntityId, string returnPath, HttpRequestData request, IOptions options, IDictionary<string, string> relayData) Sustainsys.Saml2.WebSso.SignInCommand.Run(HttpRequestData request, IOptions options) Sustainsys.Saml2.AspNetCore2.Saml2Handler.HandleRequestAsync() IdentityServer4.Hosting.FederatedSignOut.AuthenticationRequestHandlerWrapper.HandleRequestAsync() Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context) IdentityServer4.Hosting.BaseUrlMiddleware.Invoke(HttpContext context) Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

This error is coming when i am opening the signin url from the identity server 4 with Asp.net Core.

[SachinSaxena]

string samlIdentityUrl = "http://localhost:5000/Saml2"; string samlMetadataUrl = "http://localhost:5000/Saml2"; //string samlSignOnUrl = ""; string certificate = "Sustainsys.Saml2.Tests.pfx";

        services.AddAuthentication().AddSaml2(options =>
        {
            options.SignInScheme = IdentityServerConstants.ExternalCookieAuthenticationScheme;
            options.SignOutScheme = IdentityServerConstants.DefaultCookieAuthenticationScheme;
            options.SPOptions.EntityId = new EntityId(samlIdentityUrl);
            options.IdentityProviders.Add(
                new IdentityProvider(
                    new EntityId(samlMetadataUrl), options.SPOptions)
                {
                    LoadMetadata = true
                });

            options.SPOptions.ServiceCertificates.Add(new X509Certificate2(certificate));
        });

[AndersAbel]

Looks like the metadata presented by the idp is incorrect, or at least does not contain data being expected by the library.