ASP.NET Core 3.0 中 app.UseRouting 与 app.UseEndpoints

ASP.NET Core 3.0 uses a refined endpoint routing which will generally give more control about routing within the application. Endpoint routing works in two separate steps:

• In a first step, the requested route is matched agains the configured routes to figure out what route is being accessed.
• In a final step, the determined route is being evaluated and the respective middleware, e.g. MVC, is called.

　　These are two separate steps to allow other middlewares to act between those points. That allows those middlewares to utilize the information from endpoint routing, e.g. to handle authorization, without having to execute as part of the actual handler (e.g. MVC).

　　The two steps are set up by app.UseRouting() and app.UseEndpoints(). The former will register the middleware that runs the logic to determine the route. The latter will then execute that route.

　　If you read the error message carefully, between the somewhat confusing usage of EndpointRoutingMiddleware and EndpointMiddleware, it will tell you to add UseRouting() inside of the Configure method. So basically, you forgot to invoke the first step of endpoint routing.

So your Configure should (for example) look like this:

app.UseRouting();

app.UseAuthentication();

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");
    endpoints.MapRazorPages();
});