{"record":{"id":"66fee23b6f50e44f","repo":"nautechsystems/nautilus_trader","slug":"failed-to-decode-position-replay-state-e","errorCode":null,"errorMessage":"Failed to decode position replay state: {e}","messagePattern":"Failed to decode position replay state: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/infrastructure/src/redis/queries.rs","lineNumber":924,"sourceCode":"    ///\n    /// # Errors\n    ///\n    /// Returns an error if the underlying read or deserialization fails.\n    pub async fn load_position(\n        con: &ConnectionManager,\n        trader_key: &str,\n        position_id: &PositionId,\n        encoding: SerializationEncoding,\n    ) -> anyhow::Result<Option<Position>> {\n        let snapshot_key =\n            format!(\"{SNAPSHOTS}{REDIS_DELIMITER}{POSITIONS}{REDIS_DELIMITER}{position_id}\");\n        let snapshots = Self::read(con, trader_key, &snapshot_key).await?;\n        for payload in snapshots.iter().rev() {\n            let snapshot: PositionSnapshot = Self::deserialize_payload(encoding, payload)?;\n            if let Some(replay_state) = snapshot.replay_state {\n                return serde_json::from_value(replay_state)\n                    .map(Some)\n                    .map_err(|e| anyhow::anyhow!(\"Failed to decode position replay state: {e}\"));\n            }\n        }\n\n        let key = format!(\"{POSITIONS}{REDIS_DELIMITER}{position_id}\");\n        let result = Self::read(con, trader_key, &key).await?;\n        if result.is_empty() {\n            return Ok(None);\n        }\n\n        let fills: Vec<OrderFilled> = result\n            .iter()\n            .map(|payload| Self::deserialize_payload(encoding, payload))\n            .collect::<anyhow::Result<_>>()?;\n        let Some((first_fill, remaining_fills)) = fills.split_first() else {\n            return Ok(None);\n        };\n        let Some(instrument) =\n            Self::load_instrument(con, trader_key, &first_fill.instrument_id, encoding).await?","sourceCodeStart":906,"sourceCodeEnd":942,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/infrastructure/src/redis/queries.rs#L906-L942","documentation":"load_position scans position snapshots in reverse order looking for a replay_state; when found it converts the stored JSON Value into the replay-state type with serde_json::from_value. This error is thrown when that JSON value's shape does not match the expected replay state struct — i.e. the snapshot's embedded replay state is malformed or schema-drifted.","triggerScenarios":"Calling load_position when a PositionSnapshot in Redis contains a Some(replay_state) JSON object missing required fields or with wrong field types for the current ReplayState/position-state struct version.","commonSituations":"Snapshots written by an older NautilusTrader version and read by a newer one; hand-edited snapshot payloads; partially written snapshot records after a crash mid-write.","solutions":["Read the serde field path in {e} and fix that field in the stored snapshot.","Delete the offending snapshot so load_position falls back to the position events stream and rebuilds state.","Re-snapshot positions from a fresh session with the current version.","Align reader/writer versions so replay-state schemas match."],"exampleFix":"// before: old snapshot replay_state lacks required field\n{\"replay_state\": {\"last_event_id\": 5}}\n// after: provide all required fields for the current schema\n{\"replay_state\": {\"last_event_id\": 5, \"ts_last\": 1704067200000000000}}","handlingStrategy":"validation","validationCode":"// Rust: pre-validate replay_state JSON against expected struct\nfn replay_state_valid(v: &serde_json::Value) -> bool {\n    serde_json::from_value::<ReplayState>(v.clone()).is_ok()\n}","typeGuard":"fn has_replay_state(snapshot: &PositionSnapshot) -> bool {\n    snapshot.replay_state.is_some()\n}","tryCatchPattern":"match load_position(&mut con, trader_key, position_id, encoding).await {\n    Ok(pos) => pos,\n    Err(e) if e.to_string().contains(\"replay state\") => {\n        // drop stale snapshot and rebuild state from position events\n        delete_stale_snapshot(&mut con, trader_key, position_id).await?;\n        load_position(&mut con, trader_key, position_id, encoding).await.ok()\n    }\n    Err(e) => return Err(e.into()),\n}","preventionTips":["Read snapshots with the same version that wrote them; migrate or drop snapshots on upgrade.","Avoid editing snapshot payloads manually.","Verify writes complete (check acks) so snapshots are never partially stored."],"tags":["redis","positions","deserialization","schema"],"backgroundTag":"schema-validation-failed","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}