MicrosoftIdentity/Account/SignedOut show as 404

Answer from Google Bard

The error 404 means that the page "MicrosoftIdentity/Account/SignedOut" cannot be found. This can happen for a few reasons:

• The page does not exist.
• The page is not accessible to the user.
• There is a problem with the routing configuration.

To fix this error, you need to check the following:

• Make sure that the page "MicrosoftIdentity/Account/SignedOut" exists.
• Make sure that the user has permission to access the page.
• Check the routing configuration to make sure that the page is accessible.

If you are still getting the error 404, you can try the following:

• Clear the browser cache and cookies.
• Try a different browser.
• Contact the site administrator for help.

Here are some specific solutions that have worked for other people:

• If you are using the Microsoft.AspNetCore.Authentication.AzureAD.UI package, you can fix the error by adding the [AllowAnonymous] attribute to the SignOut action in the AccountController.
• If you are using the Microsoft Identity package, you can fix the error by adding the endpoints.MapRazorPages(); method to the Configure method in Startup.cs.

 

add the missing endpoints.MapRazorPages() in startup.cs works for me

 

https://nuget.info/packages/Microsoft.AspNetCore.App.Ref/3.1.10

This package was built from the source code at https://github.com/aspnet/AspNetCore/tree/e3187077455f953200e3c930430808a30f48b82e

https://github.com/dotnet/aspnetcore/blob/e3187077455f953200e3c930430808a30f48b82e/src/Mvc/Mvc.RazorPages/src/Builder/RazorPagesEndpointRouteBuilderExtensions.cs#L25

/// <summary>
        /// Adds endpoints for Razor Pages to the <see cref="IEndpointRouteBuilder"/>.
        /// </summary>
        /// <param name="endpoints">The <see cref="IEndpointRouteBuilder"/>.</param>
        /// <returns>An <see cref="PageActionEndpointConventionBuilder"/> for endpoints associated with Razor Pages.</returns>
        public static PageActionEndpointConventionBuilder MapRazorPages(this IEndpointRouteBuilder endpoints)
        {
            if (endpoints == null)
            {
                throw new ArgumentNullException(nameof(endpoints));
            }

            EnsureRazorPagesServices(endpoints);

            return GetOrCreateDataSource(endpoints).DefaultBuilder;
        }

private static void EnsureRazorPagesServices(IEndpointRouteBuilder endpoints)
        {
            var marker = endpoints.ServiceProvider.GetService<PageActionEndpointDataSource>();
            if (marker == null)
            {
                throw new InvalidOperationException(Mvc.Core.Resources.FormatUnableToFindServices(
                    nameof(IServiceCollection),
                    "AddRazorPages",
                    "ConfigureServices(...)"));
            }
        }

 private static PageActionEndpointDataSource GetOrCreateDataSource(IEndpointRouteBuilder endpoints)
        {
            var dataSource = endpoints.DataSources.OfType<PageActionEndpointDataSource>().FirstOrDefault();
            if (dataSource == null)
            {
                dataSource = endpoints.ServiceProvider.GetRequiredService<PageActionEndpointDataSource>();
                endpoints.DataSources.Add(dataSource);
            }

            return dataSource;
        }