RustPython/RustPython · error · RuntimeError

unable to write; sendfile is in progress

Error message

unable to write; sendfile is in progress

What it means

Error "unable to write; sendfile is in progress" thrown in RustPython/RustPython.

Source

Thrown at Lib/asyncio/selector_events.py:1061

                exc, 'Fatal error: protocol.eof_received() call failed.')
            return

        if keep_open:
            # We're keeping the connection open so the
            # protocol can write more, but we still can't
            # receive more, so remove the reader callback.
            self._loop._remove_reader(self._sock_fd)
        else:
            self.close()

    def write(self, data):
        if not isinstance(data, (bytes, bytearray, memoryview)):
            raise TypeError(f'data argument must be a bytes, bytearray, or memoryview '
                            f'object, not {type(data).__name__!r}')
        if self._eof:
            raise RuntimeError('Cannot call write() after write_eof()')
        if self._empty_waiter is not None:
            raise RuntimeError('unable to write; sendfile is in progress')
        if not data:
            return

        if self._conn_lost:
            if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
                logger.warning('socket.send() raised exception.')
            self._conn_lost += 1
            return

        if not self._buffer:
            # Optimization: try to send now.
            try:
                n = self._sock.send(data)
            except (BlockingIOError, InterruptedError):
                pass
            except (SystemExit, KeyboardInterrupt):
                raise
            except BaseException as exc:

View on GitHub (pinned to aaeab4f754)

When it happens

Trigger: Thrown at Lib/asyncio/selector_events.py:1061 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of RustPython/RustPython@aaeab4f754 (2026-08-17). Data as JSON: /api/errors/1d7730152701a058. Report an issue: GitHub.