Unable to serialize unknown type: <class 'taskiq.task.AsyncTaskiqTask'>

[casper-71]

Taskiq version

0.11.14

Python version

Python 3.13

OS

Linux

What happened?

After startup a worker with the result backend as RedisAsyncResultBackend the application receives an exception: PydanticSerializationError

Relevant log output

2026-02-03 15:00:00,067 - taskiq.receiver.receiver - ERROR - Can't set result in result backend. Cause: Unable to serialize unknown type: <class 'taskiq.task.AsyncTaskiqTask'>
	
		2026-02-03 17:00:00.069	
Traceback (most recent call last):
	
		2026-02-03 17:00:00.069	
  File "/usr/local/lib/python3.13/site-packages/taskiq/receiver/receiver.py", line 165, in callback
	
		2026-02-03 17:00:00.069	
    await self.broker.result_backend.set_result(taskiq_msg.task_id, result)
	
		2026-02-03 17:00:00.069	
  File "/usr/local/lib/python3.13/site-packages/taskiq_redis/redis_backend.py", line 126, in set_result
	
		2026-02-03 17:00:00.069	
    "value": self.serializer.dumpb(model_dump(result)),
	
		2026-02-03 17:00:00.069	
                                   ~~~~~~~~~~^^^^^^^^
	
		2026-02-03 17:00:00.069	
  File "/usr/local/lib/python3.13/site-packages/taskiq/compat.py", line 31, in model_dump
	
		2026-02-03 17:00:00.069	
    return instance.model_dump(mode="json")
	
		2026-02-03 17:00:00.069	
           ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
	
		2026-02-03 17:00:00.069	
  File "/usr/local/lib/python3.13/site-packages/pydantic/main.py", line 464, in model_dump
	
		2026-02-03 17:00:00.069	
    return self.__pydantic_serializer__.to_python(
	
		2026-02-03 17:00:00.069	
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
	
		2026-02-03 17:00:00.069	
        self,
	
		2026-02-03 17:00:00.069	
        ^^^^^
	
		2026-02-03 17:00:00.069	
    ...<12 lines>...
	
		2026-02-03 17:00:00.069	
        serialize_as_any=serialize_as_any,
	
		2026-02-03 17:00:00.069	
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	
		2026-02-03 17:00:00.069	
    )
	
		2026-02-03 17:00:00.069	
    ^
	
		2026-02-03 17:00:00.069	
pydantic_core._pydantic_core.PydanticSerializationError: Unable to serialize unknown type: <class 'taskiq.task.AsyncTaskiqTask'>

Broker initialization code

from taskiq import PrometheusMiddleware, SimpleRetryMiddleware, TaskiqEvents, TaskiqScheduler, TaskiqState
from taskiq.schedule_sources import LabelScheduleSource
from taskiq_pipelines import PipelineMiddleware
from taskiq_redis import ListRedisScheduleSource, RedisAsyncResultBackend, RedisStreamBroker

result_backend = RedisAsyncResultBackend(  # type: ignore
    redis_url=settings.redis.result_dsn,
    result_ex_time=settings.redis.CACHE_RESULT_EX_TIME,
    keep_results=False
)

schedule_source = ListRedisScheduleSource(url=settings.redis.schedule_dsn)


worker = (
    RedisStreamBroker(url=settings.redis.broker_dsn)
    .with_result_backend(result_backend)
    .with_middlewares(
        SimpleRetryMiddleware(default_retry_count=5),
        PipelineMiddleware(),
        PrometheusMiddleware(server_addr="0.0.0.0", server_port=9000),
    )
)

# And here's the scheduler that is used to query scheduled sources
scheduler = TaskiqScheduler(broker=worker, sources=[schedule_source, LabelScheduleSource(worker)])


@worker.on_event(TaskiqEvents.WORKER_STARTUP)
async def startup(state: TaskiqState) -> None:
    redis_pool = aioredis.ConnectionPool.from_url(url=settings.redis.cache_dsn, decode_responses=True)

    state.redis = aioredis.Redis(connection_pool=redis_pool)


@worker.on_event(TaskiqEvents.WORKER_SHUTDOWN)
async def shutdown(state: TaskiqState) -> None:
    try:
        await state.redis.disconnect()
    except AttributeError:
        await state.redis.aclose()