An error occurred while creating a route

Question

I try to add an area to my .NET Core project, but always I see that error:

RouteCreationException: An error occurred while creating the route with name '(My Area Name)'

My Code is :

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseBrowserLink();
        app.UseDeveloperExceptionPage();
        app.UseDatabaseErrorPage();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
    }

    app.UseStaticFiles();

    app.UseAuthentication();

    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");

        routes.MapRoute(
            name: "custom",
            template: "{area:my area name}/{{controller=AdminHome}/{action=Index}/{id?}");
    });
}

And in configure services I add this code:

public void ConfigureServices(IServiceCollection services)
{
    //...

    services.AddRouting(); 

    //...
}

And in controller I added:

[Area("My Area Name")]
public class AdminHomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }
}

The error is :

RouteCreationException: An error occurred while creating the route with name 'custom' and template '{area:area name}/{{controller=Home}/{action=Index}/{id?}'. \r\n Microsoft.AspNetCore.Routing.RouteBase..ctor(string template, string name, IInlineConstraintResolver constraintResolver, RouteValueDictionary defaults, IDictionary constraints, RouteValueDictionary dataTokens) \r\n ArgumentException: There is an incomplete parameter in the route template. Check that each '{' character has a matching '}' character. \r\n Parameter name: routeTemplate

Answer 1

As stated in the error message, you have a stray { in the route template that is making it invalid

template: "{area:my area name}/{{controller=AdminHome}/{action=Index}/{id?}");
                               ^
                               |
                             here

You also need to rearrange the order of routes to avoid route conflicts.

app.UseMvc(routes => {
    routes.MapRoute(
        name: "custom",
        template: "{area:my area name}/{controller=AdminHome}/{action=Index}/{id?}");

    routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");
});

Reference Areas in ASP.NET Core