Task object is not callable, when debugging with asyncio.WindowsSelectorEventLoopPolicy

Question

I have a weird situation when running the below code in debug mode in Pycharm.

It works great in run mode or in debug mode when using default policy but the default (Proactor) policy breaks another part of the application (see below)

Important: I am using WindowsSelectorEventLoopPolicy as i need to use loop.add_reader()/loop.add_writer() to the loop for sockets, and as per https://github.com/tornadoweb/tornado/issues/2608#issuecomment-619524992 I understood (and tested with success) that adding/removing readers/writers works with "Selector" event loop, but not with "Proactor" event loop, where I was getting NotImplementedErrors.

Sample code, reduced to the bare minimium :

import asyncio
import os
import sys

if sys.version_info >= (3, 8) and os.name == "nt":
    # this is required to work with loop.add_reader & co
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    # this solves the current issue but break add_reader/add_writer
    # asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())

async def main() -> None:
    print("foo")

if __name__ == '__main__':
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        pass

Result in "run" mode :

foo

Result in "debug" mode :

Exception in callback <Task pending name='Task-1'
    coro=<main() running at C:\...\a.py:21>
    cb=[_run_until_complete_cb() at C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\base_events.py:181]>()
handle: <Handle <Task pending name='Task-1'
    coro=<main() running at C:\...\a.py:21>
    cb=[_run_until_complete_cb() at C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\base_events.py:181]>()>
Traceback (most recent call last):
  File "C:\... Python.3.11_3.11.2544.0_x64__qbz5n2kfra8p0\Lib\asyncio\events.py", line 84, in _run
    self._context.run(self._callback, *self._args)
TypeError: 'Task' object is not callable

I am using python 3.11 on Windows from windows store, and PyCharm 2025.1.2 Build #PY-251.26094.141, built on June 10 2025, if it has any importance.

Andrey Aseev · Accepted Answer · 2025-08-10 15:07:36Z

2

I have just run in to the same problem with PyCharm 2025.2. After digging a little bit, I made core plugin file changes to suppress this part and side effects. Debugging still works anyway.
C:\Program Files\JetBrains\PyCharm 2025.2\plugins\python\helpers-pro\pydevd_asyncio\pydevd_nest_asyncio.py:34

if IS_ASYNCIO_DEBUGGER_ENV:

change to

if False:

(use admin permission to perform this)

answered Aug 10 at 15:07

Andrey Aseev

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Comments

Nikolai Kummer · Accepted Answer · 2025-11-04 22:32:50Z

1

The following helped me with a TypeError: 'Task' object is not callable error in PyCharm when running the debugger. I was using the scrapy library and it behaved in the same way as your error while debugging, but I suspect that you are seeing a similar issue with the asyncio library.

Press Shift twice to open the search window
From the main bar select Actions
Type in Registry and select Registry...
From here scroll down to python.debug.asyncio.repl and make sure the Value column is deselected

This is taken from the following answer: Cannot debug script with trio_asyncio in PyCharm

answered Nov 4 at 22:32

Nikolai Kummer

1771 silver badge13 bronze badges

1 Comment

Vincent Kelleher Nov 7 at 18:12

That fixed my issue, thank you ! 🙏

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