Could not find the preLaunch task ‘build’

You can use the Visual Studio Code to solve it.

When you see the error message, click on the steps below

1. Configure Task
2. Create tasks.json file from template
3. NET Core Executes .NET Core build commands

The VSCode will create a file like it:

{
    // See https://go.microsoft.com/fwlink/?LinkId=733558
    // for the documentation about the tasks.json format
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build",
            "command": "dotnet build",
            "type": "shell",
            "group": "build",
            "presentation": {
                "reveal": "silent"
            },
            "problemMatcher": "$msCompile"
        }
    ]
}

It’s finished. The VSCode will build the project before run.