vllm-project/vllm · warning · RuntimeError

Could not collect pip list output (pip or uv module not…

Error message

Could not collect pip list output (pip or uv module not available)

What it means

collect_env.py builds an environment report and lists key packages by shelling out to pip list --format=freeze. It first tries importlib.util.find_spec('pip'); if pip is absent it falls back to `uv pip list` but only when running inside a uv-managed venv (is_uv_venv()). If neither holds, it cannot enumerate packages and raises RuntimeError.

Solutions

1. Install pip into the active venv: `uv pip install pip` or ensure the venv is created by uv so is_uv_venv() matches
2. Recreate the environment with standard tooling (python -m venv with pip, or uv venv) so one of the two detection branches succeeds
3. If you only need the report, run collect_env from an environment that has pip, pointing at the same vLLM install

Example fix

# before: venv created with --without-pip, not a uv venv
$ python -m vllm.collect_env   # RuntimeError
# after
$ uv pip install pip
$ python -m vllm.collect_env

import importlib.util, sys
pip_ok = importlib.util.find_spec("pip") is not None
# plus uv-venv check; run collect_env only if pip_ok or uv venv

try:
    from vllm import collect_env
    report = collect_env.get_env()  # or CLI equivalent
except RuntimeError as e:
    if "pip list" in str(e):
        report = "package listing unavailable"
    else:
        raise

When it happens

Trigger: Running vllm.collect_env in a venv with pip deliberately stripped (e.g. uv venv without pip installed, python -m venv --without-pip), or a container where pip was removed, and the venv layout does not look like a uv venv.

Common situations: Docker images that delete pip to slim the image; uv-managed environments whose VIRTUAL_ENV/pyvenv.cfg markers differ from what is_uv_venv() expects; slim distroless-style runtimes.

Related errors

• Could not determine Python executable. Please provide it…
• Error happened when batch testing peer-to-peer access from
• failed to parse `RUST_LOG`
• Invalid wheel filename format
• io error

AI-assisted analysis of vllm-project/vllm@c794754062 (2026-08-14). Data as JSON: /api/errors/41b07b6234459863. Report an issue: GitHub.

Appendix: source

Thrown at vllm/collect_env.py:666

    if patterns is None:
        patterns = DEFAULT_PIP_PATTERNS

    def run_with_pip():
        try:
            import importlib.util

            pip_spec = importlib.util.find_spec("pip")
            pip_available = pip_spec is not None
        except ImportError:
            pip_available = False

        if pip_available:
            cmd = [sys.executable, "-mpip", "list", "--format=freeze"]
        elif is_uv_venv():
            print("uv is set")
            cmd = ["uv", "pip", "list", "--format=freeze"]
        else:
            raise RuntimeError(
                "Could not collect pip list output (pip or uv module not available)"
            )

        out = run_and_read_all(run_lambda, cmd)
        return "\n".join(
            line for line in out.splitlines() if any(name in line for name in patterns)
        )

    pip_version = "pip3" if sys.version[0] == "3" else "pip"
    out = run_with_pip()
    return pip_version, out


def get_cachingallocator_config():
    ca_config = os.environ.get("PYTORCH_CUDA_ALLOC_CONF", "")
    return ca_config

View on GitHub (pinned to c794754062)