odysseus-dev/odysseus · error · HTTPException

MLX image generator completed but did not write {out_path}

Error message

MLX image generator completed but did not write {out_path}

What it means

Raised in /v1/images/generations of scripts/mlx_image_server.py with HTTP 500 when the generation subprocess (mflux CLI, HiDream script, or Boogu in-process call) reported success but the expected output file out_path (a temp dir image.png) was not created. It guards the contract that every backend must write the output path it was given.

Source

Thrown at scripts/mlx_image_server.py:380

                if _args.base_model:
                    cmd += ["--base-model", _args.base_model]
                if _args.lora_style:
                    cmd += ["--lora-style", _args.lora_style]
                if _args.lora_paths:
                    cmd += ["--lora-paths", *_args.lora_paths]
                lora_scales = _valid_numbers(_args.lora_scales)
                if lora_scales:
                    cmd += ["--lora-scales", *lora_scales]
                if "qwen" not in model.lower():
                    cmd += ["--width", str(width), "--height", str(height)]
                env = os.environ.copy()
                proc = subprocess.run(cmd, env=env, text=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                if proc.returncode != 0:
                    detail = (proc.stderr or proc.stdout or f"{cli} failed").strip()
                    logger.error("MLX image command failed (%s): %s\n%s", proc.returncode, " ".join(cmd), detail[-4000:])
                    raise HTTPException(500, detail[-4000:])
            if not out_path.exists():
                raise HTTPException(500, f"MLX image generator completed but did not write {out_path}")
            b64 = base64.b64encode(out_path.read_bytes()).decode("ascii")
            out_images.append({"b64_json": b64})
    return {"created": 0, "data": out_images}


@app.post("/v1/images/edits")
async def edit_image(
    image: UploadFile = File(...),
    mask: UploadFile | None = File(None),
    prompt: str = Form(""),
    model: str = Form(""),
    n: int = Form(1),
    size: str = Form("1024x1024"),
    response_format: str = Form("b64_json"),
):
    active_model = model or _args.model
    if _is_lama_inpaint(active_model) or _is_ddcolor(active_model):
        image_raw = await image.read()

View on GitHub (pinned to f9235ebbf1)

Solutions

1. Reproduce the exact logged command manually and check where output lands
2. Upgrade/align the backend version with what the server expects for --output
3. Freeze/inspect the temp dir (replace TemporaryDirectory with a kept dir) to see whether the file appears then vanishes
4. Check disk space and temp dir permissions on the host

# server-side guard: verify backend writes before accepting traffic
subprocess.run([cli, '--model', m, '--prompt', 'smoke', '--steps', '1', '--output', '/tmp/probe.png'], check=True)
assert pathlib.Path('/tmp/probe.png').exists()

try:
    gen_and_read(out_path)
except HTTPException as e:
    if 'did not write' in str(e.detail):
        out_path = run_backend_manually_and_locate_output()  # fallback path
    else:
        raise

When it happens

Trigger: A backend exits 0 without producing the file: CLI wrote to a different location (output flag mishandled), HiDream script saved elsewhere or silently skipped saving, Boogu path failed to save without raising, or temp-dir permission issues.

Common situations: Version change in mflux/HiDream script renaming the --output semantics; quantized forks that print instead of save; sandboxed temp dirs cleaned mid-run; disk-full so the save silently no-ops in the child.

Related errors

• MLX Swift bridge completed but did not write {out_path}
• detail[-4000:]
• HiDream generator script not found in snapshot: {script}
• d.error || 'Failed to create calendar'
• Failed to delete calendar

AI-assisted analysis of odysseus-dev/odysseus@f9235ebbf1 (2026-08-14). Data as JSON: /api/errors/44e19cf8652c7b89. Report an issue: GitHub.