CLR attach fails with configurationDone 0x80070057 on .NET Framework (Windows)

[nivkush]

When attaching the debugger to a .NET Framework 4.x process (e.g. ASP.NET Web API running under IIS Express), the CLR attach fails with:

Failed command 'configurationDone' : 0x80070057

Environment:

• OS: Windows 10/11 (build [your build if known])
• Editor: Cursor [version] (or VS Code [version])
• Extension(s): C# (ms-dotnettools.csharp) [version], C# Dev Kit (ms-dotnettools.csdevkit) [version if installed]

App being debugged: .NET Framework 4.x (ASP.NET Web API on IIS Express).

launch.json attach configuration:

Using type: "clr", request: "attach", with either processName or processId:

{
    "name": "Attach to IIS Express",
    "type": "clr",
    "request": "attach",
    "processName": "iisexpress",
    "cwd": "${workspaceFolder}",
    "requireExactSource": false
}

Also occurs with configs that use processId (numeric or from an input like "${input:attachPid}").

Steps to reproduce:

1. Open a .NET Framework solution in Cursor/VS Code.
2. Start the app (e.g. IIS Express) so the process is running.
3. Run and Debug → select the CLR attach config (e.g. "Attach to IIS Express") → F5.
4. The error Failed command 'configurationDone' : 0x80070057 appears and attach does not complete.

[gregg-miskelly]

Unfortunately, that error message isn't very good.

Is your iisexpress.exe process a 32-bit process?

[nivkush]

im trying to attach the project to iis

    {
        "name": "Attach to Process (enter PID when prompted)",
        "type": "clr",
        "request": "attach",
        "processId": "${input:attachPid}",
        "cwd": "${workspaceFolder}",
        "requireExactSource": false
    },

and get this error
Failed command 'configurationDone' : 0x80070057

[gregg-miskelly]

Yes, I understand. Try this:

1. Open Task Manager
2. Switch to the details tab
3. If you don't have a "Platform" column, add it
4. Find iisexpress.exe in the list

What do you see for "Platform"?

[gregg-miskelly]

Also, can you add this to your "Attach to Process" configuration in launch.json and tell me what you get in the debug console?

            "logging": {
                "diagnosticsLog": {
                    "debugEngineAPITracing": "error"
                }
            }

[nivkush]

i dont have iisexpress because the apps are running on the iis

this is what i have

[nivkush]

and when i use the logging i dont get nothing in the debug console only the error
Failed command 'configurationDone' : 0x80070057

{
"version": "0.2.0",
"configurations": [
{
"name": "Attach to Process",
"type": "clr",
"request": "attach",
"cwd": "${workspaceFolder}",
"requireExactSource": false,
"logging": {
"diagnosticsLog": {
"debugEngineAPITracing": "error"
}
}
},
]
}

this is my launch.json

[nivkush]

also when i do this from VS Code i get this message

You may only use the Microsoft Visual Studio .NET/C/C++ Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software to help you
develop and test your applications.

[gregg-miskelly]

i dont get nothing in the debug console only the error

Interesting. Can you try this instead in case it provides something more useful:

            "logging": {
                "diagnosticsLog": {
                    "protocolMessages": true,
                    "debugEngineAPITracing": "all"
                }
            }

also when i do this from VS Code i get this message

That is normal. It will always show up.

[gregg-miskelly]

i dont have iisexpress because the apps are running on the iis

I am confused then -- didn't you say you were trying to attach to issexpress? Or are you trying both?

[nivkush]

both and nothing is working for my