What causes "pip not found" in LykosAI/StabilityMatrix?

Recreate the venv via Setup() ensuring pip is included (no --without-pip).

LykosAI/StabilityMatrix · error · FileNotFoundException

pip not found

Error message

pip not found

What it means

PipInstall() throws FileNotFoundException when the venv's pip executable (PipPath, e.g. Scripts/pip.exe or bin/pip) does not exist. The library will not spawn a pip command without a working pip inside the venv. Usually means the venv was created without pip or was never fully initialized.

Solutions

Recreate the venv via Setup() ensuring pip is included (no --without-pip).
Run `python -m ensurepip` against the venv interpreter to restore pip.
Verify PipPath exists before calling: File.Exists(venvRunner.PipPath).
Confirm RootPath and BaseInstall point at the intended, intact venv.

Example fix

// before
await venvRunner.PipInstall("numpy");
// after
if (!File.Exists(venvRunner.PipPath))
{
    await venvRunner.Setup(null, null, ct); // recreate venv with pip
}
await venvRunner.PipInstall("numpy");

Defensive patterns

Strategy: validation

Validate before calling

if (!File.Exists(venvRunner.PipPath))
{
    await venvRunner.Setup(null, null, ct);
}

Try / catch

catch (FileNotFoundException e) when (e.FileName == venvRunner.PipPath)
{
    // recreate venv, then retry the pip operation
}

Prevention

Create venvs with pip included (never --without-pip).
Check PipPath existence as a preflight before batch pip operations.
Avoid uninstalling pip itself from the venv.

When it happens

Trigger: Calling PipInstall() on a venv created without pip (e.g. `python -m venv --without-pip`), a venv whose creation failed partway, or a PyVenvRunner whose RootPath/PythonPath configuration points to a venv lacking pip.

Common situations: Venv created with pip omitted; pip later uninstalled from the venv; corrupted/incomplete venv after failed setup or interrupted upgrade; wrong RootPath pointing to a non-venv folder.

Related errors

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/0340d924d11573db. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Core/Python/PyVenvRunner.cs:228

        cfg["home"] = pythonDirectory;
        cfg["base-prefix"] = pythonDirectory;
        cfg["base-exec-prefix"] = pythonDirectory;
        cfg["base-executable"] = baseExecutable;
        cfg.Save(cfgPath);

        // Update last set path
        lastSetPyvenvCfgPath = pythonDirectory;
    }

    /// <summary>
    /// Run a pip install command. Waits for the process to exit.
    /// workingDirectory defaults to RootPath.
    /// </summary>
    public async Task PipInstall(ProcessArgs args, Action<ProcessOutput>? outputDataReceived = null)
    {
        if (!File.Exists(PipPath))
        {
            throw new FileNotFoundException("pip not found", PipPath);
        }

        // Record output for errors
        var output = new StringBuilder();

        var outputAction = new Action<ProcessOutput>(s =>
        {
            Logger.Debug($"Pip output: {s.Text}");
            // Record to output
            output.Append(s.Text);
            // Forward to callback
            outputDataReceived?.Invoke(s);
        });

        RunDetached(args.Prepend("-m pip install").Concat("--exists-action s"), outputAction);
        await Process.WaitForExitAsync().ConfigureAwait(false);

        // Check return code

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