{"record":{"id":"6b77ecf205f3dd1d","repo":"nautechsystems/nautilus_trader","slug":"cannot-persist-position-with-no-events","errorCode":null,"errorMessage":"Cannot persist position with no events: {}","messagePattern":"Cannot persist position with no events: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/infrastructure/src/redis/cache.rs","lineNumber":1264,"sourceCode":"        self.send_command(DatabaseOperation::Update, key, Some(vec![payload]))\n    }\n\n    fn serialize_account_event(&self, account: &AccountAny) -> anyhow::Result<Bytes> {\n        let event: AccountState = account.last_event().ok_or_else(|| {\n            anyhow::anyhow!(\"Cannot persist account with no events: {}\", account.id())\n        })?;\n        let payload = DatabaseQueries::serialize_payload(self.encoding(), &event)?;\n        Ok(Bytes::from(payload))\n    }\n\n    fn serialize_order_event(&self, order_event: &OrderEventAny) -> anyhow::Result<Bytes> {\n        let payload = DatabaseQueries::serialize_payload(self.encoding(), order_event)?;\n        Ok(Bytes::from(payload))\n    }\n\n    fn serialize_position_event(&self, position: &Position) -> anyhow::Result<Bytes> {\n        let event: OrderFilled = position.last_event().ok_or_else(|| {\n            anyhow::anyhow!(\"Cannot persist position with no events: {}\", position.id)\n        })?;\n        let payload = DatabaseQueries::serialize_payload(self.encoding(), &event)?;\n        Ok(Bytes::from(payload))\n    }\n\n    fn load_state(&self, key: String) -> anyhow::Result<AHashMap<String, Bytes>> {\n        let mut con = self.database.con.clone();\n        let trader_key = self.database.trader_key.clone();\n        let encoding = self.encoding();\n        let (tx, rx) = mpsc::channel();\n\n        get_runtime().spawn(async move {\n            let result = async {\n                let full_key = format!(\"{trader_key}{REDIS_DELIMITER}{key}\");\n                let value: Option<Bytes> = con.get(&full_key).await?;\n                let Some(value) = value else {\n                    return Ok(AHashMap::new());\n                };","sourceCodeStart":1246,"sourceCodeEnd":1282,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/infrastructure/src/redis/cache.rs#L1246-L1282","documentation":"When persisting a Position to the Redis cache, the adapter serializes the position's last event. This error means the Position has no event at all (`position.last_event()` returned None), so there is nothing to serialize. The library refuses to write a stateless position because a persisted position without events could not be reconstructed on load.","triggerScenarios":"Calling `update_position(position)` (via the cache `update_actor`/position persist path) with a Position instance that was constructed but never received an event (e.g. a position initialized from a fill-less event or a manually built Position passed to `Position::update` was never invoked).","commonSituations":"Restoring or migrating positions from external data where events were not replayed; custom backtest/live code that constructs a Position directly and pushes it into the cache before processing any order-filled events; bugs in custom position handling in a strategy or custom adapter.","solutions":["Ensure the Position has been updated via `position.update(event)` (which sets `last_event`) before calling any cache persist/update API","Check that order fill events are actually flowing to the position (event generation ordering in the execution engine or custom adapter)","If migrating state, replay the original position events from the journal before persisting","Log the position id to find which position is eventless and inspect how it was created"],"exampleFix":"// before\nlet position = Position::new(&event); // if created without events and persisted immediately\ncache.update_position(&position)?;\n// after\nlet mut position = Position::new(&event);\nposition.update(&fill_event); // ensures last_event is Some\ncache.update_position(&position)?;","handlingStrategy":"validation","validationCode":"// Rust\nif position.last_event().is_none() {\n    return Err(anyhow::anyhow!(\"refusing to persist position {} with no events\", position.id));\n}\ncache.update_position(&position)?;","typeGuard":"fn has_events(position: &Position) -> bool {\n    position.last_event().is_some()\n}","tryCatchPattern":null,"preventionTips":["Always drive positions through the execution engine so events are recorded before persistence","Assert `last_event().is_some()` in debug builds before persisting","When importing/migrating positions, replay their events first","Log position id at creation sites to trace eventless positions quickly"],"tags":["redis","cache","position","serialization"],"backgroundTag":"empty-required-field","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}