VS 2026: Docker Compose: Cannot debug ASP.NET Framework 4.7 project with IIS windows container

[kamranayub]

Been using VS 2022 with Container Tools for months now without too much of an issue.

I just upgraded to VS 2026 this week and everything is working... except debugging.

I have a web project that is .NET Framework 4.7.1 and is configured to run under IIS in Windows Server Core 2022.

FROM mcr.microsoft.com/dotnet/framework/aspnet:4.8-windowsservercore-ltsc2022 

# etc...

WORKDIR /inetpub/wwwroot
COPY ${source:-obj/Docker/publish} .

The docker compose project is configured to launch the web project/service:

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" Sdk="Microsoft.Docker.Sdk">
  <PropertyGroup Label="Globals">
    <ProjectVersion>2.1</ProjectVersion>
    <DockerTargetOS>Windows</DockerTargetOS>
    <DockerPublishLocally>True</DockerPublishLocally>
    <ProjectGuid>69dae30f-922a-4e5a-b2a3-3baf4a11c33b</ProjectGuid>
    <DockerLaunchAction>LaunchBrowser</DockerLaunchAction>
    <DockerServiceUrl>http://{ServiceHost}:{ServicePort}</DockerServiceUrl>
    <DockerServiceName>web</DockerServiceName>
  </PropertyGroup>
  <ItemGroup>
    <None Include="docker-compose.override.yml">
      <DependentUpon>docker-compose.yml</DependentUpon>
    </None>
    <None Include="docker-compose.yml" />
  </ItemGroup>
</Project>

I have two profiles, but worth noting I've only been using the first one. I added the second explicitly to try and figure out why VS2026 wasn't working:

{
  "profiles": {
    "Docker Compose": {
      "commandName": "DockerCompose",
      "commandVersion": "1.0",
      "serviceActions": {
        "web": "StartWithoutDebugging",
        "db": "StartWithoutDebugging",
        "api": "StartWithoutDebugging",
        "jobs": "StartWithoutDebugging"
      }
    },
    "Debug Website": {
      "commandName": "DockerCompose",
      "commandVersion": "1.0",
      "composeLaunchServiceName": "web",
      "serviceActions": {
        "api": "StartWithoutDebugging",
        "db": "StartWithoutDebugging",
        "jobs": "StartWithoutDebugging",
        "web": "StartDebugging"
      }
    }
  }
}

One obvious thing I notice is that in VS 2026, the Docker Compose startup settings is not mapping my projects correctly in the GUI:

Notice too how it is not mapping the "StartDebugging" value either for the web service.

I think this is a regression but it's hard to debug. Maybe I'm missing a component in VS2026 installation that I have in VS2022? As a workaround, I can debug still in VS2022.

[kamranayub]

Just wanted to mention, this is still an issue, but I will test the latest 2026 December Update. I've been using VS 2022 instead. I may need to report this on the feedback portal I suppose?

https://developercommunity.visualstudio.com/VisualStudio

[kamranayub]

Logged here: https://developercommunity.visualstudio.com/t/Cannot-debug-ASPNET-MVC5-Framework-in-D/11015986?port=1025&fsid=109e6451-13a1-4f5f-b0da-4494ff72f791

[kamranayub]

Follow up from that report: Apparently this is not planned to be fixed. Which is a massive bummer because you are not "supposed" to run .NET 10 in VS2022. But I am, and all my projects besides my legacy web project are .NET 10.

So now I'm stuck between a rock and hard place, which is really irritating when .NET Framework is at least supposed to be maintained for legacy projects.

Either:

1. I have to use VS2026 and not be able to debug my web project, i.e. the main project that I'm working on day-to-day
2. I have to use VS2022 and not install VS2026 in the hopes I can maintain .NET 10 working "unofficially"

[NCarlsonMSFT]

@kamranayub how often do you need to debug the Full Framework project? If your issue in VS 2026 is that the .csproj and Dockerfile being together causes the compose tools to try and fail to debug the service, you can set the label "com.microsoft.visual-studio.project-name" to null or empty string to make break the connection between the project and service and disable our no longer supported attempts at debugging. Is that enough to unblock you?

P.S. for debugging you should be able to use the Attach To container dialog, you may need to deploy the VS remote debugger 1st, but I think it will even do that for you.

[kamranayub]

@kamranayub how often do you need to debug the Full Framework project? If your issue in VS 2026 is that the .csproj and Dockerfile being together causes the compose tools to try and fail to debug the service, you can set the label "com.microsoft.visual-studio.project-name" to null or empty string to make break the connection between the project and service and disable our no longer supported attempts at debugging. Is that enough to unblock you?

P.S. for debugging you should be able to use the Attach To container dialog, you may need to deploy the VS remote debugger 1st, but I think it will even do that for you.

Interesting, I could try that... I do need to debug often enough each session since it's the primary project I make changes in, but it depends if the feature I'm working on is mostly in the React side or C#.