ASP.NET Core docker build error

Solution 1:

It is docker-compose.dcproj file where you can set up the OS you want to target:

<DockerTargetOS>Linux</DockerTargetOS>

To switch docker daemon to the same OS you can use Docker tray icon or Docker Settings window (accessible from the same menu):

Solution 2:

Well basically the answer of Celestin Bochis and Pavel Agarkov are great. However since .net core 2.2 at least, the os of docker is stored in the .csproj file.

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
    ...
   </PropertyGroup>

   ...
</Project>

And also don't forget to modify your docker file. The images should be the correct one. For .net core 2.2 That is :

Linux:
Microsoft/dotnet:2.2-aspnetcore-runtime AS base
microsoft/dotnet:2.2-sdk AS build

Windows:
microsoft/dotnet:2.2-aspnetcore-runtime-nanoserver-1803
microsoft/dotnet:2.2-sdk-nanoserver-1803

Solution 3:

Make sure to choose the correct OS when you Enable docker support:

Your docker daemon has to target Linux containers as well.