Error Handling

Common Error Scenarios

Error	Cause	Solution
Logon Rejected	Invalid client_id or secret	Verify OAuth credentials with 360X support
Session Disconnected	Heartbeat timeout	Ensure heartbeat generation is working
Duplicate Session	Multiple connections with same SenderCompID	Logout from previous session first

Error	Cause	Solution
Order Rejected: Unknown ISIN	Invalid SecurityID	Request SecurityList first, use valid ISIN
Order Rejected: Invalid Price	Price validation failed	Check minimum price increment for instrument
Cancel Rejected	Order already filled	Handle partial fills, check order status first
Replace Rejected	Order not found	Verify ClOrdID, check order still exists

Error	Cause	Solution
Quote Request Rejected	Invalid counterparty LEI	Validate LEI format (20 characters)
Quote Rejected	Price outside valid range	Check market prices before quoting
Quote Cancel Failed	Quote already accepted	Handle race condition gracefully

Error	Cause	Solution
MsgSeqNum Too Low	Sequence number already seen	Check for duplicate sends, resend if needed
MsgSeqNum Too High	Gap detected	Send ResendRequest for missing messages
Sequence Number Mismatch	Session state desync	Reset session (ResetOnLogon=Y) or reconcile

Rejection messages typically include:

Tag 58 (Text): Human-readable error description

Tag 372 (RefMsgType): Message type that was rejected

Tag 373 (SessionRejectReason): Standardized reason code

Example Rejection:

8=FIXT.1.1|9=XXX|35=3|
58=Required tag missing: SecurityID (48)|
372=D|373=1|
10=XXX|