Your first ASP.NET Core application

Understand the idea

An ASP.NET Core application is a running .NET process that receives HTTP requests and produces responses. MVC gives that process a useful structure: controllers coordinate work, models describe data, and views turn data into HTML. Your editor helps you write and debug the code, but the SDK is what actually builds it.

In this curriculum you will explore TaskBoard, a deliberately small application with real accounts and a persistent database. You can run the finished application from the first lesson, then work through each feature with the relevant source beside you. This avoids the frustrating gap between an isolated snippet and a project that actually compiles.

Verify your development tools

In Visual Studio Installer, select the ASP.NET and web development workload and use a release that supports .NET 10. In VS Code, install C# Dev Kit and open the folder containing the project file. Both environments use the same SDK and source.

Open a terminal and check the installed SDKs. You should see a 10.0.x entry. If you only see older SDKs, install .NET 10 before proceeding. Restart your editor after installation so it picks up changes to PATH.

dotnet --list-sdks
dotnet --info

Run the companion project

Download and extract TaskBoard from the example projects page. Enter the TaskBoard directory, restore packages, and run it. The launch profile selects Development and listens at http://localhost:5300. The first development startup applies the included migrations and creates a local SQLite file.

Open the printed address in your browser. Register a learning account, then create your first task. Stop the application with Ctrl+C, run it again, and sign back in. Your task survives because it is stored in the database, rather than in a JavaScript array.

cd TaskBoard
dotnet restore
dotnet run

Read the project map

The project file selects the framework and NuGet dependencies. Program.cs registers services and builds the HTTP pipeline. Controllers handle requests; Views contains Razor templates; Models contains entities and input models. Data holds the database context and migrations. Static CSS lives under wwwroot.

Open Controllers/HomeController.cs. Index returns View(), so MVC looks for Views/Home/Index.cshtml. That file uses the shared layout for navigation and styling. Change the heading in the view, save it, and rerun to see a change you own.

using Microsoft.AspNetCore.Mvc;

namespace TaskBoard.Controllers;

public class HomeController : Controller
{
    public IActionResult Index() => View();
    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
    public IActionResult Error() => View("Error", HttpContext.TraceIdentifier);
}

Create a clean MVC project yourself

The downloaded project contains several completed features. To see the baseline separately, create a fresh project in another directory with the MVC template. Use a different port so the two applications do not compete for the same address.

Place a breakpoint inside HomeController.Index. In Visual Studio press F5. In VS Code open Run and Debug and choose the C# project; let C# Dev Kit create or select the launch configuration. Visit the homepage and inspect the HttpContext.Request.Path value when execution stops.

dotnet new mvc -n FirstMvc -f net10.0
cd FirstMvc
dotnet run -- --urls http://localhost:5301

When something doesn't work

“Address already in use” means another process owns the port. Stop that application or choose a different port.

“SDK not found” or NETSDK1045 means the selected SDK cannot target .NET 10. Inspect dotnet --info and check whether a parent global.json pins an older SDK.

A SQLite “no such table” error usually means you launched outside the Development profile or skipped migrations. Run dotnet tool restore and dotnet ef database update from the sample project directory.