Invalid Directory Name on Starting a Resource Added with AddPnpmApp

[brady-kelly]

I'm trying to get a Nextjs app using pnpm running in my Aspire solution, but the resource fails to start with the following logged:

Executing command 'resource-start'.
Successfully executed command 'resource-start'.
[sys] Starting process...: Cmd = C:\Program Files\nodejs\pnpm.cmd, Args = ["install"]
 [sys] Failed to start a process: Cmd = C:\Program Files\nodejs\pnpm.cmd, Args = ["install"], Error = fork/exec C:\Program Files\nodejs\pnpm.cmd: The directory name is invalid.
 [sys] Failed to start Executable: Error = fork/exec C:\Program Files\nodejs\pnpm.cmd: The directory name is invalid.

The directory and file do exist on my Windows 11 file system. The pnpm.cmd file contents are:

@SETLOCAL
@IF EXIST "%~dp0\node.exe" (
  "%~dp0\node.exe"  "%~dp0\node_modules\corepack\dist\pnpm.js" %*
) ELSE (
  @SET PATHEXT=%PATHEXT:;.JS;=;%
  node  "%~dp0\node_modules\corepack\dist\pnpm.js" %*
)

I'm adding the resource with this code in app host:

var nextFrontend = builder
    .AddPnpmApp("frontend", ".​.​/​frontend", "dev")
    .WithWorkingDirectory(Path.GetFullPath("../frontend"))
    .WithPnpmPackageInstallation()
    .WaitFor(server)
    .WithReference(server)
    .WithHttpEndpoint(env: "PORT") 
    .WithExternalHttpEndpoints();

[shreyanshjain1]

This looks less like a missing file problem and more like a how the process is being started on Windows problem.

pnpm.cmd is a batch wrapper, not a real executable, so if Aspire is trying to fork/exec it directly, Windows can throw weird errors like this even when the file definitely exists.

The clue for me is that the path is valid, the file exists, but the failing command is still:

C:\Program Files\nodejs\pnpm.cmd

I’d suspect the process needs to be started through cmd.exe /c instead of trying to execute the .cmd file directly.

So I’d check 3 things:

1. whether AddPnpmApp / WithPnpmPackageInstallation() is invoking pnpm.cmd directly on Windows
2. whether using plain pnpm from PATH behaves differently than hard-resolving C:\Program Files\nodejs\pnpm.cmd
3. whether forcing execution through cmd /c pnpm install avoids the issue

Since pnpm.cmd itself just forwards into Node/Corepack, another thing worth trying is avoiding the wrapper entirely and testing whether calling through Corepack works better on this machine.

So this feels like one of these:

• Windows .cmd wrapper execution issue
• Aspire Windows process-launch bug / limitation
• path resolution issue specifically around pnpm.cmd instead of pnpm

If you want a quick sanity check, I’d try replacing the pnpm invocation path with a cmd /c pnpm ... style launch and see if the problem disappears. If it does, then the issue is probly not your working directory at all, but the direct execution of the .cmd wrapper.