LykosAI/StabilityMatrix · error · FileNotFoundException

pip not found

Error message

pip not found

What it means

UvVenvRunner.PipIndex throws FileNotFoundException("pip not found", PipPath) before running `python -m pip index versions` when the pip executable path for the base install does not exist on disk. The library refuses to spawn a process with a missing binary, so this signals the venv/base Python install is incomplete or was never set up.

Solutions

1. Ensure pip exists in the venv: run `uv pip install --python <venvPython> pip` or recreate the venv with seeding.
2. Use the uv-based PipInstall/PipShow paths (which use UvExecutablePath) instead of PipIndex when the venv has no pip.
3. Verify BaseInstall.RootPath points at a real Python install and PipPath matches the OS layout (Scripts\pip.exe on Windows, bin/pip on Unix).
4. Re-setup the venv via UvVenvRunner if the directory was partially deleted.

Example fix

// before: assuming pip always exists in the venv
await runner.PipIndex("torch");
// after: guard first, fall back to a uv-backed path
if (!File.Exists(runner.PipPath)) {
    await runner.PipInstall(new ProcessArgs("--upgrade", "pip")); // seeds pip via uv
}
await runner.PipIndex("torch");

if (!File.Exists(runner.PipPath)) {
    await runner.PipInstall(new ProcessArgs("--upgrade", "pip")); // seed pip via uv
}

static bool HasPip(UvVenvRunner r) => File.Exists(r.PipPath);

try { await runner.PipIndex(pkg); }
catch (FileNotFoundException ex) { Logger.Error($"pip missing: {ex.FileName}"); await EnsurePipAsync(); }

When it happens

Trigger: Calling PipIndex(packageName) when File.Exists(PipPath) is false — the venv's pip script/Scripts path is absent because the venv was created without pip (uv-created venvs often omit pip by default) or the base install is broken/deleted.

Common situations: Venvs created via `uv venv` (which does not install pip unless --seed is used); a partially cleaned or moved install directory; wrong BaseInstall pointing at a non-Python directory; platform path differences (Scripts vs bin).

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• get-pip not found
• pip not found
• pyvenv.cfg not found
• pip not found
• Venv python not found

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/f8bf5397a5576dbb. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Core/Python/UvVenvRunner.cs:420

                $"pip show returned no output for package '{packageName}': {result.StandardError}"
            );
        }

        return PipShowResult.Parse(result.StandardOutput);
    }

    /// <summary>
    /// Run a pip index command, return result as PipIndexResult.
    /// </summary>
    public async Task<PipIndexResult?> PipIndex(
        string packageName,
        string? indexUrl = null,
        bool includePrerelease = false
    )
    {
        if (!File.Exists(PipPath))
        {
            throw new FileNotFoundException("pip not found", PipPath);
        }

        SetPyvenvCfg(BaseInstall.RootPath);

        var args = new ProcessArgsBuilder(
            "-m",
            "pip",
            "index",
            "versions",
            packageName,
            "--no-color",
            "--disable-pip-version-check"
        );

        if (indexUrl is not null)
        {
            args = args.AddKeyedArgs("--index-url", ["--index-url", indexUrl]);
        }

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