datawhalechina/hello-agents · error · HTTPException

Task '{task_id}' not found

Error message

Task '{task_id}' not found

What it means

GET /tasks/{task_id} returns HTTP 404 when task_manager.get(task_id) raises KeyError — the task id does not exist in the (in-memory or persisted) task store. Task ids are generated by POST /tasks, so any id not issued by that endpoint (or lost after a restart of an in-memory store) triggers this.

Source

Thrown at Co-creation-projects/huailishang-AgentPlatformBase/backend/main.py:93

@app.post("/tasks", response_model=TaskRecord)
def create_task(request: TaskCreateRequest) -> TaskRecord:
    if request.agent_id not in set(registry.ids()):
        raise HTTPException(status_code=404, detail=f"Agent '{request.agent_id}' not found")
    return task_manager.create(request)


@app.get("/tasks")
def list_tasks() -> dict:
    tasks = task_manager.list()
    return {"tasks": tasks, "total": len(tasks)}


@app.get("/tasks/{task_id}", response_model=TaskRecord)
def get_task(task_id: str) -> TaskRecord:
    try:
        return task_manager.get(task_id)
    except KeyError:
        raise HTTPException(status_code=404, detail=f"Task '{task_id}' not found")


@app.post("/tasks/{task_id}/run", response_model=TaskRecord)
def run_task(task_id: str, background: bool = True) -> TaskRecord:
    try:
        task_manager.get(task_id)
    except KeyError:
        raise HTTPException(status_code=404, detail=f"Task '{task_id}' not found")
    if background:
        return task_runner.start_background(task_id)
    return task_runner.run(task_id)


@app.post("/batch/run")
def run_batch(request: BatchRunRequest) -> dict:
    try:
        return {"responses": batch_runner.run(request.requests)}
    except KeyError as exc:

View on GitHub (pinned to 606a07d341)

Solutions

  1. GET /tasks (list) to confirm which task ids currently exist, then use one of those.
  2. If tasks must survive restarts, back task_manager with persistent storage instead of memory.
  3. Re-create the task via POST /tasks if it was lost to a restart.
  4. Double-check the id for truncation or whitespace when copying.

Example fix

# before
resp = requests.get(f"{BASE}/tasks/{task_id}")  # 404 after restart

# after
if resp.status_code == 404:
    existing = {t["id"] for t in requests.get(f"{BASE}/tasks").json()["tasks"]}
    if task_id not in existing:
        task_id = requests.post(f"{BASE}/tasks", json=original_payload).json()["id"]
        resp = requests.get(f"{BASE}/tasks/{task_id}")
Defensive patterns

Strategy: try-catch

Validate before calling

existing = {t["id"] for t in requests.get(f"{BASE}/tasks").json()["tasks"]}
if task_id not in existing:
    raise LookupError(f"task {task_id} not found; recreate via POST /tasks")

Type guard

def task_exists(task_id: str, existing_ids: set[str]) -> bool:
    return task_id in existing_ids

Try / catch

try:
    resp = requests.get(f"{BASE}/tasks/{task_id}")
    resp.raise_for_status()
except HTTPError as e:
    if e.response.status_code == 404:
        task = requests.post(f"{BASE}/tasks", json=original_create_payload).json()  # recreate after restart
        task_id = task["id"]
    else:
        raise

Prevention

When it happens

Trigger: GET /tasks/<stale-id> after the backend restarted with an in-memory task manager; a truncated/copy-pasted task id; querying a task created on a different backend instance.

Common situations: Backend restarts wiping in-memory task state; multiple environments (dev/prod) confusing saved task ids; typos in ids saved in scripts or notebooks.

Related errors

AI-assisted analysis of datawhalechina/hello-agents@606a07d341 (2026-08-14). Data as JSON: /api/errors/385bdf21afed109d. Report an issue: GitHub.