{"record":{"id":"9a3562633fa77d11","repo":"python/cpython","slug":"cannot-close-a-running-event-loop-9a3562","errorCode":null,"errorMessage":"Cannot close a running event loop","messagePattern":"Cannot close a running event loop","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"Lib/asyncio/proactor_events.py","lineNumber":682,"sourceCode":"\n    def _make_duplex_pipe_transport(self, sock, protocol, waiter=None,\n                                    extra=None):\n        return _ProactorDuplexPipeTransport(self,\n                                            sock, protocol, waiter, extra)\n\n    def _make_read_pipe_transport(self, sock, protocol, waiter=None,\n                                  extra=None):\n        return _ProactorReadPipeTransport(self, sock, protocol, waiter, extra)\n\n    def _make_write_pipe_transport(self, sock, protocol, waiter=None,\n                                   extra=None):\n        # We want connection_lost() to be called when other end closes\n        return _ProactorWritePipeTransport(self,\n                                           sock, protocol, waiter, extra)\n\n    def close(self):\n        if self.is_running():\n            raise RuntimeError(\"Cannot close a running event loop\")\n        if self.is_closed():\n            return\n\n        if threading.current_thread() is threading.main_thread():\n            signal.set_wakeup_fd(-1)\n        # Call these methods before closing the event loop (before calling\n        # BaseEventLoop.close), because they can schedule callbacks with\n        # call_soon(), which is forbidden when the event loop is closed.\n        self._stop_accept_futures()\n        self._close_self_pipe()\n        self._proactor.close()\n        self._proactor = None\n        self._selector = None\n\n        # Close the event loop\n        super().close()\n\n    async def sock_recv(self, sock, n):","sourceCodeStart":664,"sourceCodeEnd":700,"githubUrl":"https://github.com/python/cpython/blob/bc6749cc3b5ae4a5e88a6cc2d5b3bebbe354eae6/Lib/asyncio/proactor_events.py#L664-L700","documentation":"Error \"Cannot close a running event loop\" thrown in python/cpython.","triggerScenarios":"Raised when loop.close() is called on a running proactor event loop.","commonSituations":"See trigger scenarios.","solutions":["Stop the proactor event loop (loop.stop()) and let run_forever() return before calling loop.close().","Use asyncio.run() / asyncio.Runner to manage the loop lifecycle automatically."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"bc6749cc3b5ae4a5e88a6cc2d5b3bebbe354eae6","analyzedAt":"2026-08-14T22:01:13.976Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}