vllm - 💡(How to fix) Fix [Bug]: GLM chat template crashes with "'None' has no attribute 'items'" when tool_call arguments is the string "null" [2 pull requests]

vLLM v0.20.1 confirmed affected.
Model: zai-org/GLM-5.1-FP8
Startup flags: --tool-call-parser glm47 --reasoning-parser glm45 --enable-auto-tool-choice --chat-template-content-format string

---

import json, urllib.request, urllib.error, os

payload = {
    "model": os.environ["VLLM_MODEL"],
    "messages": [
        {"role": "user", "content": "What time is it?"},
        {
            "role": "assistant",
            "content": None,
            "tool_calls": [{
                "id": "call_1",
                "type": "function",
                "function": {"name": "get_current_time", "arguments": "null"},
            }],
        },
        {"role": "tool", "tool_call_id": "call_1", "content": "14:32 UTC"},
    ],
    "tools": [{
        "type": "function",
        "function": {
            "name": "get_current_time",
            "description": "Returns the current server time.",
            "parameters": {"type": "object", "properties": {}, "required": []},
        },
    }],
    "max_tokens": 64,
}

req = urllib.request.Request(
    f"{os.environ['VLLM_BASE_URL']}/v1/chat/completions",
    data=json.dumps(payload).encode(),
    headers={"Content-Type": "application/json", "Authorization": f"Bearer {os.environ['VLLM_API_KEY']}"},
    method="POST",
)
try:
    urllib.request.urlopen(req, timeout=30)
except urllib.error.HTTPError as e:
    print(e.read().decode())

---

HTTP 400: {"error": {"message": "'None' has no attribute 'items'", "type": "BadRequestError", "param": null, "code": 400}}