How to attach debugger for ASP.NET Core web site running in IIS targeting net47?

Question

I just converted a large legacy site to Net Core. Because of some old code, I have to target net47 instead of netcoreapp2.0 / netstandard2.0.

Problem is that when I run the site in IIS, it starts up correctly, but then I cannot attach the debugger. The process list (Debug | Attach to process) does not show the dotnet.exe process at all.

To investigate this:

• I created a new ASP.NET Core web application in Visual Studio 2017 targeting netcoreapp2.0,
• published it (dotnet publish) and
• pointed my IIS web site to the published directory.

After hitting the site, I was able to attach to the dotnet.exe process ok. Here is the .csproj file:

 <Project Sdk="Microsoft.NET.Sdk.Web"> <!-- dotnet.exe shows up in process list in Visual Studio 2017 --> <PropertyGroup> <TargetFramework>netcoreapp2.0</TargetFramework> </PropertyGroup> <ItemGroup> <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.3" /> </ItemGroup> <ItemGroup> <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.1" /> </ItemGroup> </Project> 

I then retargeted it to net47 because that is what my site uses.

• Because Microsoft.AspNetCore.All does not support net47, I replaced it with enough individual packages to make the site compile.
• Published it (dotnet publish -f net47).
• Pointed the IIS site to the new net47 published directory.

I could load the site ok and navigate around. However, dotnet.exe no longer appeared in the process list.

 <Project Sdk="Microsoft.NET.Sdk.Web"> <!-- dotnet.exe does NOT show up in process list in Visual Studio 2017 --> <PropertyGroup> <TargetFramework>net47</TargetFramework> </PropertyGroup> <ItemGroup> <PackageReference Include="Microsoft.AspNetCore" Version="2.0.*" /> <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.0.*" /> <PackageReference Include="Microsoft.Extensions.Configuration" Version="2.0.*" /> <PackageReference Include="Microsoft.Extensions.Logging" Version="2.0.*" /> <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="2.0.*" /> <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.0.*" /> <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.0.*" /> <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.0.*" /> <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.0.*" /> <PackageReference Include="Microsoft.VisualStudio.Web.BrowserLink" Version="2.0.*" /> </ItemGroup> <ItemGroup> <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.1" /> </ItemGroup> </Project> 

Is there any way I can debug a site running in IIS that targets the Net Framework?

Answer 1

It's my experience that you must attach to the process name that matches your web application's executable; the default value is the project name.

Answer 2

Does w3wp.exe appear? If so, see if selecting that for debugging works. If it's targeting 47 and running in IIS, it may be using IIS's w3wp process.

This is a guess given what I saw; not in a position to verify at the moment. Let me know if it works!