FIX Error: Tag 371 Missing ClOrdID – Explained
Tag 371 (RefTagID) in a FIX Reject message indicates that the original message was rejected because ClOrdID (tag 11) was missing. ClOrdID is a mandatory field for all order-related messages including NewOrderSingle (35=D), OrderCancelRequest (35=F), and OrderCancelReplaceRequest (35=G).
Root Cause
The most common causes are: 1) Application logic fails to populate ClOrdID before sending the order, 2) Message construction library omits the field, 3) Field filtering removes ClOrdID incorrectly, or 4) Message validation passes but field is empty.
Broker/Exchange Action
The broker/exchange will reject the message with a session-level reject (MsgType=3) including RefTagID=371 and SessionRejectReason=6 (Required tag missing). The order will not be processed.
Client/Your Action
1) Verify ClOrdID generation logic is called before message construction, 2) Ensure ClOrdID is unique per session (or per day if required), 3) Check that no message filtering removes tag 11, 4) Validate ClOrdID is non-empty before sending, 5) Use UUID or timestamp-based IDs to ensure uniqueness.
Example FIX Message
How FIX Doctor Detects This
FIX Doctor scans all order messages (35=D, F, G, 8) and flags any message missing tag 11. The error appears in the 'Detected Issues' section with severity 'error' and includes suggested fix instructions.
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