ASP.NET Core site can't find Default route on startup

Question

I add a route named default with the pattern

{controller=Assets}/{action=Index}/{id?}

but I get an http 404 "Not Found" error.

If I type in /Assets in the browser, it finds the view, it's just on the first request.

This issue occurred after installing VS 2026 and the latest SDKs.

Any ideas?

Configuring WebApplicationBuilder:

_ = builder.Services.AddControllersWithViews(mvcOptions);

Adding the route named default:

app.MapControllerRoute(ruteName, pattern);

Edit: fixed it by adding Assets as start url in launch profiles.

Please create the answer post but not edit the question. Can I answer my own question? — Yong Shun
– Yong Shun, Commented Nov 17 at 8:28

SteinTech · Accepted Answer · 2025-11-17 10:07:18Z

2

The documentation states that the route named 'default' will be loaded on a root request, but I'm unable to get it to work.

However, you can add the controller name to the URL option in Launch Profiles in Visual Studio.

Debug > Project name Debug Properties

It works, but I would prefer setting the startup route in code.

answered Nov 17 at 10:07

SteinTech

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