Mar 10, 2026 · Mar 9, 2026
diff --git a/Lib/asyncio/base_subprocess.py b/Lib/asyncio/base_subprocess.py
            # to avoid hanging forever in self._wait as otherwise _exit_waiters
            # would never be woken up, we wake them up here.
            for waiter in self._exit_waiters:
                if not waiter.cancelled():
                if not waiter.done():
                    waiter.set_result(self._returncode)
        if all(p is not None and p.disconnected
               for p in self._pipes.values()):
        finally:
            # wake up futures waiting for wait()
            for waiter in self._exit_waiters:
                if not waiter.cancelled():
                if not waiter.done():
                    waiter.set_result(self._returncode)
            self._exit_waiters = None
            self._loop = None
diff --git a/Lib/test/test_asyncio/test_subprocess.py b/Lib/test/test_asyncio/test_subprocess.py
        )
 transport.close()

 deftest_proc_exited_no_invalid_state_error_on_exit_waiters(self):
 # gh-145541: when _connect_pipes hasn't completed (so
 # _pipes_connected is False) and the process exits, _try_finish()
 # sets the result on exit waiters. Then _call_connection_lost() must
 # not call set_result() again on the same waiters.
 self.loop.set_exception_handler(
 lambdaloop,context:self.fail(
 f"unexpected exception:{context}")
        )
 waiter=self.loop.create_future()
 transport,protocol=self.create_transport(waiter)

 # Simulate a waiter registered via _wait() before the process exits.
 exit_waiter=self.loop.create_future()
 transport._exit_waiters.append(exit_waiter)

 # _connect_pipes hasn't completed, so _pipes_connected is False.
 self.assertFalse(transport._pipes_connected)

 # Simulate process exit. _try_finish() will set the result on
 # exit_waiter because _pipes_connected is False, and then schedule
 # _call_connection_lost() because _pipes is empty (vacuously all
 # disconnected). _call_connection_lost() must skip exit_waiter
 # because it's already done.
 transport._process_exited(6)
 self.loop.run_until_complete(waiter)

 self.assertEqual(exit_waiter.result(),6)

 transport.close()


 classSubprocessMixin:

diff --git a/Misc/NEWS.d/next/Library/2026-03-05-19-01-28.gh-issue-145551.gItPRl.rst b/Misc/NEWS.d/next/Library/2026-03-05-19-01-28.gh-issue-145551.gItPRl.rst
 Fix InvalidStateError when cancelling process created by :func:`asyncio.create_subprocess_exec` or :func:`asyncio.create_subprocess_shell`. Patch by Daan De Meyer.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -265,7 +265,7 @@ def _try_finish(self):
		# to avoid hanging forever in self._wait as otherwise _exit_waiters
		# would never be woken up, we wake them up here.
		for waiter in self._exit_waiters:
		if not waiter.cancelled():
		if not waiter.done():
		waiter.set_result(self._returncode)
		if all(p is not None and p.disconnected
		for p in self._pipes.values()):
Expand All		@@ -278,7 +278,7 @@ def _call_connection_lost(self, exc):
		finally:
		# wake up futures waiting for wait()
		for waiter in self._exit_waiters:
		if not waiter.cancelled():
		if not waiter.done():
		waiter.set_result(self._returncode)
		self._exit_waiters = None
		self._loop = None
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -111,6 +111,37 @@ def test_subprocess_repr(self):
		)
		transport.close()

		deftest_proc_exited_no_invalid_state_error_on_exit_waiters(self):
		# gh-145541: when _connect_pipes hasn't completed (so
		# _pipes_connected is False) and the process exits, _try_finish()
		# sets the result on exit waiters. Then _call_connection_lost() must
		# not call set_result() again on the same waiters.
		self.loop.set_exception_handler(
		lambdaloop,context:self.fail(
		f"unexpected exception:{context}")
		)
		waiter=self.loop.create_future()
		transport,protocol=self.create_transport(waiter)

		# Simulate a waiter registered via _wait() before the process exits.
		exit_waiter=self.loop.create_future()
		transport._exit_waiters.append(exit_waiter)

		# _connect_pipes hasn't completed, so _pipes_connected is False.
		self.assertFalse(transport._pipes_connected)

		# Simulate process exit. _try_finish() will set the result on
		# exit_waiter because _pipes_connected is False, and then schedule
		# _call_connection_lost() because _pipes is empty (vacuously all
		# disconnected). _call_connection_lost() must skip exit_waiter
		# because it's already done.
		transport._process_exited(6)
		self.loop.run_until_complete(waiter)

		self.assertEqual(exit_waiter.result(),6)

		transport.close()


		classSubprocessMixin:

Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix InvalidStateError when cancelling process created by :func:`asyncio.create_subprocess_exec` or :func:`asyncio.create_subprocess_shell`. Patch by Daan De Meyer.