{"record":{"id":"2567002730b60610","repo":"nautechsystems/nautilus_trader","slug":"error-no-ask-orders-for-best-ask-price","errorCode":null,"errorMessage":"Error: No ask orders for best ask price","messagePattern":"Error: No ask orders for best ask price","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"critical","filePath":"crates/model/src/ffi/orderbook/book.rs","lineNumber":273,"sourceCode":"/// Panics if there are no bid orders for best bid price.\n#[unsafe(no_mangle)]\n#[cfg_attr(feature = \"high-precision\", allow(improper_ctypes_definitions))]\npub extern \"C\" fn orderbook_best_bid_price(book: &mut OrderBook) -> Price {\n    abort_on_panic(|| {\n        book.best_bid_price()\n            .expect(\"Error: No bid orders for best bid price\")\n    })\n}\n\n/// # Panics\n///\n/// Panics if there are no ask orders for best ask price.\n#[unsafe(no_mangle)]\n#[cfg_attr(feature = \"high-precision\", allow(improper_ctypes_definitions))]\npub extern \"C\" fn orderbook_best_ask_price(book: &mut OrderBook) -> Price {\n    abort_on_panic(|| {\n        book.best_ask_price()\n            .expect(\"Error: No ask orders for best ask price\")\n    })\n}\n\n/// # Panics\n///\n/// Panics if there are no bid orders for best bid size.\n#[unsafe(no_mangle)]\n#[cfg_attr(feature = \"high-precision\", allow(improper_ctypes_definitions))]\npub extern \"C\" fn orderbook_best_bid_size(book: &mut OrderBook) -> Quantity {\n    abort_on_panic(|| {\n        book.best_bid_size()\n            .expect(\"Error: No bid orders for best bid size\")\n    })\n}\n\n/// # Panics\n///\n/// Panics if there are no ask orders for best ask size.","sourceCodeStart":255,"sourceCodeEnd":291,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/model/src/ffi/orderbook/book.rs#L255-L291","documentation":"This panic fires in the FFI wrapper `orderbook_best_ask_price` when `OrderBook::best_ask_price()` returns None because the ask side of the book has no orders. Since the wrapper runs under `abort_on_panic`, the process aborts instead of returning a recoverable error across the FFI boundary.","triggerScenarios":"Calling `orderbook_best_ask_price(book)` on a book with an empty ask side: no ask quotes/depth levels received yet, all asks removed, or the book was recently cleared/created.","commonSituations":"Subscribing to trade-only data (no asks populated); a partial depth snapshot containing only bids; querying during a data gap or before the feed warms up; stale books after a disconnect where levels were deleted.","solutions":["Guard the call by checking the ask side is non-empty before invoking the FFI function.","Populate the book from a full initial depth snapshot before querying best ask.","Treat a missing best ask explicitly (return None) and skip spread/midpoint logic that depends on it.","Confirm the market-data subscription includes ask-side updates (quotes or depth) for the instrument."],"exampleFix":"// before (Python FFI caller)\nbest_ask = orderbook_best_ask_price(book)\n// after\nif has_ask_orders(book):\n    best_ask = orderbook_best_ask_price(book)\nelse:\n    best_ask = None","handlingStrategy":"validation","validationCode":"def can_get_best_ask(book) -> bool:\n    return book.has_orders() and book.asks_len() > 0","typeGuard":"def has_ask_side(book) -> bool:\n    try:\n        return len(book.asks()) > 0\n    except Exception:\n        return False","tryCatchPattern":null,"preventionTips":["Check ask-side presence before querying best ask","Ensure depth/quote subscriptions include ask updates","Re-check after clear/reset operations before any book queries","Treat empty books as an expected state and query optional accessors instead of FFI panicking ones","Remember FFI panics abort the process — they cannot be caught as exceptions"],"tags":["rust","ffi","orderbook","panic","process-abort"],"backgroundTag":"empty-result-set","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"}