你可以使用: 在ConfigureServices方法中:

services.AddControllersWithViews();

配置方法:

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

我发现这个问题是由于. net Core框架的更新。最新发布的。net Core 3.0版本需要显式地选择使用MVC。

当人们试图从旧的。net Core(2.2或预览3.0版本)迁移到。net Core 3.0时，这个问题最为明显

如果从2.2迁移到3.0，请使用下面的代码来修复这个问题。

services.AddMvc(options => options.EnableEndpointRouting = false);

如果使用。net Core 3.0模板，

services.AddControllers(options => options.EnableEndpointRouting = false);

修改后的ConfigServices方法如下所示:

谢谢你！

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        //Old Way
        services.AddMvc();
        // New Ways
        //services.AddRazorPages();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseStaticFiles();
        app.UseRouting();
        app.UseCors();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllerRoute("default", "{controller=Home}/{action=Index}");
        });
    }
}

这也适用于。net Core 5

对于DotNet核心3.1

使用下面的

文件:Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{         

    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
       
    app.UseHttpsRedirection();
    app.UseRouting();
    app.UseAuthentication();
    app.UseHttpsRedirection();
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

但我需要知道正确的解决方法是什么

通常，您应该使用EnableEndpointRouting而不是UseMvc，并且您可以参考更新路由启动代码以获得启用EnableEndpointRouting的详细步骤。

为什么端点路由不需要UseMvc()函数。

对于UseMvc，它使用基于irouter的逻辑，而EnableEndpointRouting使用基于端点的逻辑。他们遵循不同的逻辑，可以在下面找到:

if (options.Value.EnableEndpointRouting)
{
    var mvcEndpointDataSource = app.ApplicationServices
        .GetRequiredService<IEnumerable<EndpointDataSource>>()
        .OfType<MvcEndpointDataSource>()
        .First();
    var parameterPolicyFactory = app.ApplicationServices
        .GetRequiredService<ParameterPolicyFactory>();

    var endpointRouteBuilder = new EndpointRouteBuilder(app);

    configureRoutes(endpointRouteBuilder);

    foreach (var router in endpointRouteBuilder.Routes)
    {
        // Only accept Microsoft.AspNetCore.Routing.Route when converting to endpoint
        // Sub-types could have additional customization that we can't knowingly convert
        if (router is Route route && router.GetType() == typeof(Route))
        {
            var endpointInfo = new MvcEndpointInfo(
                route.Name,
                route.RouteTemplate,
                route.Defaults,
                route.Constraints.ToDictionary(kvp => kvp.Key, kvp => (object)kvp.Value),
                route.DataTokens,
                parameterPolicyFactory);

            mvcEndpointDataSource.ConventionalEndpointInfos.Add(endpointInfo);
        }
        else
        {
            throw new InvalidOperationException($"Cannot use '{router.GetType().FullName}' with Endpoint Routing.");
        }
    }

    if (!app.Properties.TryGetValue(EndpointRoutingRegisteredKey, out _))
    {
        // Matching middleware has not been registered yet
        // For back-compat register middleware so an endpoint is matched and then immediately used
        app.UseEndpointRouting();
    }

    return app.UseEndpoint();
}
else
{
    var routes = new RouteBuilder(app)
    {
        DefaultHandler = app.ApplicationServices.GetRequiredService<MvcRouteHandler>(),
    };

    configureRoutes(routes);

    routes.Routes.Insert(0, AttributeRouting.CreateAttributeMegaRoute(app.ApplicationServices));

    return app.UseRouter(routes.Build());
}

对于EnableEndpointRouting，它使用EndpointMiddleware将请求路由到端点。

这对我很有效

 services.AddMvc(options => options.EnableEndpointRouting = false); or 
 OR
 services.AddControllers(options => options.EnableEndpointRouting = false);