## SOLVED • uvicorn required uvloop, and the presence of uvloop triggered the error described below Ideally, prefect gets updated to play nice with uvicorn/uvloop and/or fails if uvloop is present with a more direct error. ## OP Hi, I'm trying to get up and running from 1.x to 2.x going from agents to workers. The error being provided is giving me no insight to the problem, and would appreciate any guidance. Using docker compose .. the containers are linux running on mac with the following containers:

(prefect-server, prefect-worker-init <-- pool creation, prefect-worker-sync, prefect-worker-publish)

and a

prefect.yaml

file ### Python Version • 3.11.x ### prefect.yaml

- name: User Sync
    description: "Sync user data"
    schedule:
      interval: 60
      timezone: UTC
    entrypoint: src/flows/sync.py:sync_users
    parameters: {}
    work_pool:
      name: sync-pool
      work_queue_name: default

### Output from

prefect-worker-sync

2024-02-09 13:55:41 18:55:41.271 | INFO    | prefect.flow_runs.worker - Opening process...
2024-02-09 13:55:41 18:55:41.274 | DEBUG   | prefect.flow_runs.worker - Process running command: /opt/app-root/bin/python -m prefect.engine in /tmp/tmp2lc5l6b1prefect
2024-02-09 13:55:41 18:55:41.276 | ERROR   | prefect.flow_runs.worker - Failed to submit flow run '21fd9312-f9d6-426d-bdcc-1824342fc6ad' to infrastructure.
2024-02-09 13:55:41 Traceback (most recent call last):
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/prefect/workers/base.py", line 896, in _submit_run_and_capture_errors
2024-02-09 13:55:41     result = await self.run(
2024-02-09 13:55:41              ^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/prefect/workers/process.py", line 185, in run
2024-02-09 13:55:41     process = await run_process(
2024-02-09 13:55:41               ^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/prefect/utilities/processutils.py", line 258, in run_process
2024-02-09 13:55:41     async with open_process(
2024-02-09 13:55:41   File "/usr/lib64/python3.11/contextlib.py", line 204, in __aenter__
2024-02-09 13:55:41     return await anext(self.gen)
2024-02-09 13:55:41            ^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/prefect/utilities/processutils.py", line 202, in open_process
2024-02-09 13:55:41     process = await anyio.open_process(command, **kwargs)
2024-02-09 13:55:41               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/anyio/_core/_subprocesses.py", line 126, in open_process
2024-02-09 13:55:41     return await get_asynclib().open_process(
2024-02-09 13:55:41            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/opt/app-root/lib64/python3.11/site-packages/anyio/_backends/_asyncio.py", line 1041, in open_process
2024-02-09 13:55:41     process = await asyncio.create_subprocess_exec(
2024-02-09 13:55:41               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/usr/lib64/python3.11/asyncio/subprocess.py", line 221, in create_subprocess_exec
2024-02-09 13:55:41     transport, protocol = await loop.subprocess_exec(
2024-02-09 13:55:41                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/usr/lib64/python3.11/asyncio/base_events.py", line 1694, in subprocess_exec
2024-02-09 13:55:41     transport = await self._make_subprocess_transport(
2024-02-09 13:55:41                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/usr/lib64/python3.11/asyncio/unix_events.py", line 198, in _make_subprocess_transport
2024-02-09 13:55:41     with events.get_child_watcher() as watcher:
2024-02-09 13:55:41          ^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/usr/lib64/python3.11/asyncio/events.py", line 811, in get_child_watcher
2024-02-09 13:55:41     return get_event_loop_policy().get_child_watcher()
2024-02-09 13:55:41            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2024-02-09 13:55:41   File "/usr/lib64/python3.11/asyncio/events.py", line 637, in get_child_watcher
2024-02-09 13:55:41     raise NotImplementedError

### compose.yml

prefect-worker-init:
      entrypoint: []
      command: |-
        sh -c '
          prefect work-pool create --type process sync-pool
          prefect work-pool update --concurrency-limit 2 sync-pool
          prefect --no-prompt deploy --all &&
          true
        '

  prefect-worker-sync:
    entrypoint:
      [
        "prefect",
        "worker",
        "start",
        "-p",
        "sync-pool",
        "--with-healthcheck"
      ]
    environment:
      - APPLICATION_NAME=local.pipeline
    volumes:
      - ./sync:/app
    healthcheck:
      test:
        [
          "CMD-SHELL",
          "httpx <http://127.0.0.1:8080/health> || exit 1"
        ]
      interval: 10s
      timeout: 30s
      retries: 5
    depends_on:
      prefect-server:
        condition: service_started
      prefect-worker-init:
        condition: service_completed_successfully