Processor Architecture Mismatch Warning (MSB3270) During Docker-Compose Build

[zugzwangm]

Processor Architecture Mismatch Warning (MSB3270) During Docker-Compose Build

Description

When using a Docker Compose project with an ASP.NET Core application (tested on versions 8 and 9), and setting the ASP.NET platform target to x64 (due to the use of native packages), the Docker Compose build phase generates the following warning:

warning MSB3270: There was a mismatch between the processor architecture of the project being built "MSIL" and the processor architecture of the reference "<ASPNET project DLL>", "AMD64".

Steps to Reproduce

1. Create a Docker Compose project with an ASP.NET Core application.
2. Set the platform target for the ASP.NET project to x64 (typically needed when using native packages).
3. Build.

Environment

• Visual Studio: Tested on 17.11.x and 17.12.0
• ASP.NET Core: Tested on .NET 8 and .NET 9

Additional Information

• The mismatch is between the docker-compose project architecture ("MSIL"; why is it MSIL?) and the referenced ASP.NET DLL ("AMD64").

Workaround

The workaround provided by @NCarlsonMSFT works great!

[NCarlsonMSFT]

The warning is harmless as the compose project doesn't have real output referencing the csproj. As a workaround you can change the "platform" of the .dcproj

<PropertyGroup>
  <PlatformTarget>x64</PlatformTarget>
</PropertyGroup>