python runtime_error ai_generated true

RuntimeError: no running event loop

ID: python/no-running-event-loop

Also available as: JSON · Markdown · 中文
80%Fix Rate
89%Confidence
0Evidence
2024-01-22First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.8 active — — —
3.9 active — — —
3.10 active — — —
3.11 active — — —
3.12 active — — —

Root Cause

asyncio.get_running_loop() (or an API that calls it internally, like asyncio.create_task) was invoked from synchronous code outside any running loop.

generic

中文

在没有任何正在运行的循环的同步代码中调用了 asyncio.get_running_loop()（或内部调用它的 API，如 asyncio.create_task）。

Workarounds

  1. 95% success 
    Only call create_task/get_running_loop from inside a coroutine:

async def main():
    asyncio.create_task(worker())

asyncio.run(main())
  2. 85% success 
    From sync code that must schedule work, use asyncio.run_coroutine_threadsafe when you have a loop reference:

future = asyncio.run_coroutine_threadsafe(coro(), loop)
  3. 80% success 
    In Jupyter/IPython, use `await` directly in the cell, or call nest_asyncio.apply() once at the top of the notebook.

Dead Ends

Common approaches that don't work:

  1. 55% fail

    Deprecated since 3.10 and emits DeprecationWarning; in 3.12 it still raises when no loop is set.

  2. 95% fail

    Makes it worse — guarantees no loop is available.

  3. 90% fail

    Timing has nothing to do with loop presence.