nautechsystems/nautilus_trader · error

Cannot reopen position {} (oms_type=NETTING): reopening is o

Error message

Cannot reopen position {} (oms_type=NETTING): reopening is only valid for closed positions in NETTING mode

What it means

OmsType guard in reopen_position: under NETTING a position may only be reopened after it was closed; attempting to reopen a position that is not closed would corrupt netting net-position accounting and is rejected.

Source

Thrown at crates/execution/src/engine/mod.rs:4279

        let ts_init = self.clock.borrow().timestamp_ns();
        let event = PositionOpened::create(&position, &fill, UUID4::new(), ts_init);

        Ok(vec![PositionEvent::PositionOpened(event)])
    }

    fn is_duplicate_closed_fill(position: &Position, fill: &OrderFilled) -> bool {
        position.replay_events.iter().any(|event| {
            matches!(
                event,
                PositionReplayEvent::Filled(replayed) if replayed.trade_id == fill.trade_id
            )
        })
    }

    fn reopen_position(&self, position: &Position, oms_type: OmsType) -> anyhow::Result<()> {
        if oms_type == OmsType::Netting {
            if position.is_open() {
                anyhow::bail!(
                    "Cannot reopen position {} (oms_type=NETTING): reopening is only valid for closed positions in NETTING mode",
                    position.id
                );
            }
        } else {
            // HEDGING mode
            log::warn!(
                "Received fill for closed position {} in HEDGING mode; archiving closed cycle and creating new position",
                position.id
            );
        }

        // Snapshot the closed cycle before its ID is reused: `add_position` replaces the
        // cached position, and realized PnL totals read closed cycles from the snapshots
        self.snapshot_position(position)?;

        Ok(())
    }

View on GitHub (pinned to 18893faf8b)

Solutions

1. Let the position close before resubmitting orders that would reopen it
2. Review the fill sequence producing fills against a non-closed position

When it happens

Trigger: Thrown at crates/execution/src/engine/mod.rs:4279 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/1006742cddd82def. Report an issue: GitHub.