FIX Error: Missing Side (54) – How to Fix
Tag 54 (Side) specifies whether an order is a Buy (1) or Sell (2). This field is mandatory for all order messages including NewOrderSingle, OrderCancelReplaceRequest, and ExecutionReports that reference orders.
Root Cause
Common causes: 1) Order entry UI doesn't capture side, 2) Message builder omits Side field, 3) Side value is null or empty string, 4) Incorrect FIX version where Side wasn't mandatory (legacy systems).
Broker/Exchange Action
Broker rejects with RefTagID=54, SessionRejectReason=6. Order is not accepted.
Client/Your Action
1) Ensure Side is captured from order entry, 2) Set Side=1 for Buy, Side=2 for Sell, 3) Validate Side is present and valid before sending, 4) Check FIX version requirements.
Example FIX Message
How FIX Doctor Detects This
FIX Doctor checks all order messages for presence of tag 54. Missing Side triggers an error with suggested fix.
Related Errors
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