BerriAI/litellm · error · ProcessLaunchError

Ephemeral proxy exited early (code {process.returncode}). La

Error message

Ephemeral proxy exited early (code {process.returncode}). Last log lines:
{_tail(log_path)}

What it means

The spawned ephemeral proxy process terminated before its liveliness endpoint answered; the launcher reports the exit code plus the last 40 log lines to expose startup failures (bad config, port conflict).

Source

Thrown at litellm/proxy/client/cli/commands/autoroute/process.py:101

            ],
            stdout=log_file,
            stderr=subprocess.STDOUT,
        )


def _tail(log_path: Path, lines: int = 40) -> str:
    if not log_path.exists():
        return "(no log output captured)"
    return "\n".join(log_path.read_text(errors="replace").splitlines()[-lines:])


def poll_liveliness(base_url: str, log_path: Path, process: "subprocess.Popen[bytes]", timeout: float = 30.0) -> None:
    """Poll /health/liveliness until it responds, the process dies, or timeout elapses."""
    deadline: Final = time.monotonic() + timeout
    url: Final = base_url.rstrip("/") + "/health/liveliness"
    while time.monotonic() < deadline:
        if process.poll() is not None:
            raise ProcessLaunchError(
                f"Ephemeral proxy exited early (code {process.returncode}). Last log lines:\n{_tail(log_path)}"
            )
        with contextlib.suppress(requests.RequestException):
            if requests.get(url, timeout=2).status_code == 200:
                return
        time.sleep(0.5)
    raise ProcessLaunchError(
        f"Ephemeral proxy never became healthy within {timeout}s. Last log lines:\n{_tail(log_path)}"
    )


def write_pid_record(record: PidRecord, path: Path | None = None) -> None:
    resolved_path: Final = path if path is not None else PID_RECORD_PATH
    resolved_path.parent.mkdir(parents=True, exist_ok=True)
    with open(resolved_path, "w") as f:
        json.dump(
            {"pid": record.pid, "port": record.port, "config_path": record.config_path, "log_path": record.log_path},
            f,

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Read the logged tail lines to find why the proxy exited.
2. Fix the proxy config/port conflict and retry.

Example fix

Check the ephemeral proxy log file shown in the error message.

When it happens

Trigger: Thrown at litellm/proxy/client/cli/commands/autoroute/process.py:101 when the library encounters an invalid state.

Common situations: The ephemeral proxy process crashed during startup.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/a975f4dbf6ecfa63. Report an issue: GitHub.