MemPalace/mempalace · error · SystemExit

2

2

Error message

Writable MCP HTTP startup refused: %s

What it means

Error "Writable MCP HTTP startup refused: %s" thrown in MemPalace/mempalace.

Source

Thrown at mempalace/mcp_server.py:7992

            break


def _run_http_loop() -> None:
    # In HTTP mode there is no JSON-RPC stdio channel. Keeping the import-time
    # stdout->stderr guard in place means any accidental print from a dependency
    # still cannot masquerade as an HTTP response.
    logger.info("MemPalace MCP HTTP server starting...")

    # A writable HTTP server is a long-lived storage client, so it must own the
    # local palace before it binds. Refusing at startup avoids advertising a
    # writable service that will only fail (or race) on its first mutation.
    # Explicit read-only HTTP remains safe to run beside the one writer owner.
    owns_writer_lease = False
    if not _READ_ONLY:
        writer_ok, writer_reason = _acquire_mcp_writer_lock()
        if not writer_ok:
            logger.error("Writable MCP HTTP startup refused: %s", writer_reason)
            raise SystemExit(2)
        owns_writer_lease = True

    try:
        # The HTTP transport exists for long-lived deployments. Do the cheap
        # filesystem-only probe before binding, but never make the listener wait on
        # optional embedder/HNSW warmup. Operators and tests should see /healthz as
        # soon as the process is alive.
        _refresh_vector_disabled_flag()
        _start_idle_exit_watchdog()
        _start_write_stall_watchdog()

        raw_warmup = os.environ.get("MEMPALACE_EAGER_WARMUP", "").strip().lower()
        if raw_warmup in _WARMUP_TRUTHY:

            def _warmup_with_lock():
                with _HTTP_REQUEST_LOCK:
                    _maybe_eager_warmup_embedder()

View on GitHub (pinned to 06cb6987f0)

Solutions

1. Stop the existing writable owner, or route writes through it

When it happens

Trigger: Thrown at mempalace/mcp_server.py:7992 when the library encounters an invalid state.

Common situations: Another writable MCP/direct/daemon owner already holds the local backend.

AI-assisted analysis of MemPalace/mempalace@06cb6987f0 (2026-08-15). Data as JSON: /api/errors/a45abb360ea3ff77. Report an issue: GitHub.