LykosAI/StabilityMatrix · error · ProcessException

Venv creation failed with code

Error message

Venv creation failed with code {venvProc.ExitCode}

What it means

Setup() launches `python -m venv` as a subprocess and throws ProcessException if the venv creation process exits with a non-zero exit code. This means the Python interpreter failed to build the virtual environment (bad interpreter, corrupted base install, disk/permission problems).

Solutions

1. Inspect captured console output (onConsoleOutput) for the underlying Python error message.
2. Delete the partially created venv directory, re-download/reinstall the base Python (PyInstall), and retry Setup.
3. Verify the base Python executable runs standalone: `<basePython> --version`.
4. Free disk space and check no processes hold locks on the venv directory (Windows).

if (!File.Exists(baseInstall.PythonPath)) throw new InvalidOperationException("Base Python missing");

catch (ProcessException e)
{
    Logger.Error("venv creation failed: {Msg}", e.Message);
    await venvRunner.DeleteAsync(ct); // clean partial state
    throw;
}

When it happens

Trigger: Calling Setup() when the base Python executable is broken/incompatible (e.g. mismatched embedded Python version), the target disk is full, or antivirus blocks venv creation, causing the venv subprocess to return non-zero.

Common situations: Corrupted or half-deleted base Python install (BaseInstall path changed after upgrade); insufficient disk space; Windows file locks on python.exe from a previous process; embedded Python download incomplete.

Related errors

• Venv creation failed with code
• pip show failed with code
• Venv python not found
• Torch is not installed in the virtual environment.
• ComfyUI venv was not found at

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/e50ff25f2d304d49. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Core/Python/PyVenvRunner.cs:167

        // Create venv (copy mode if windows)
        var args = new string[] { "-m", "virtualenv", Compat.IsWindows ? "--always-copy" : "", RootPath };

        var venvProc = ProcessRunner.StartAnsiProcess(
            BaseInstall.PythonExePath,
            args,
            WorkingDirectory?.FullPath,
            onConsoleOutput
        );

        try
        {
            await venvProc.WaitForExitAsync(cancellationToken).ConfigureAwait(false);

            // Check return code
            if (venvProc.ExitCode != 0)
            {
                throw new ProcessException($"Venv creation failed with code {venvProc.ExitCode}");
            }
        }
        catch (OperationCanceledException)
        {
            venvProc.CancelStreamReaders();
        }
        finally
        {
            venvProc.Kill();
            venvProc.Dispose();
        }
    }

    /// <summary>
    /// Set current python path to pyvenv.cfg
    /// This should be called before using the venv, in case user moves the venv directory.
    /// </summary>
    private void SetPyvenvCfg(string pythonDirectory, bool force = false)

View on GitHub (pinned to af93d6ef57)