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Common NewOrderSingle (35=D) Errors and How to Diagnose Them

NewOrderSingle (35=D) is one of the most critical FIX messages. Missing or invalid fields can cause immediate rejects and trading failures. This guide covers the most common errors and how to fix them.

Missing ClOrdID (Tag 11)

Problem: Every NewOrderSingle must have a unique ClOrdID (Client Order ID).

8=FIX.4.4|9=123|35=D|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|38=100|56=TARGET|10=123|
❌ Missing: 11=ClOrdID

Fix: Add a unique ClOrdID: 11=ORDER12345

Correct Example:

8=FIX.4.4|9=123|35=D|11=ORDER12345|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|38=100|56=TARGET|10=123|
✓ Includes ClOrdID

Missing Side (Tag 54)

Problem: Side (54) is mandatory and must be 1 (Buy) or 2 (Sell).

8=FIX.4.4|9=123|35=D|11=ORDER123|34=1|49=SENDER|52=20240101-10:00:00|55=AAPL|38=100|56=TARGET|10=123|
❌ Missing: 54=Side

Fix: Add Side: 54=1 (Buy) or 54=2 (Sell)

Missing Symbol (Tag 55)

Problem: Symbol (55) identifies the security being traded.

8=FIX.4.4|9=123|35=D|11=ORDER123|34=1|49=SENDER|52=20240101-10:00:00|54=1|38=100|56=TARGET|10=123|
❌ Missing: 55=Symbol

Fix: Add Symbol: 55=AAPL

Missing OrderQty (Tag 38)

Problem: OrderQty (38) is required for NewOrderSingle and OrderCancelReplaceRequest.

8=FIX.4.4|9=123|35=D|11=ORDER123|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|40=2|44=150.00|56=TARGET|10=123|
❌ Missing: 38=OrderQty

Fix: Add OrderQty: 38=100

Missing Price (Tag 44) for Limit Orders

Problem: Limit orders (OrdType=2) require Price (44).

8=FIX.4.4|9=123|35=D|11=ORDER123|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|38=100|40=2|56=TARGET|10=123|
❌ Missing: 44=Price (required for Limit order)

Fix: Add Price: 44=150.00

Proper Example vs Faulty Example

❌ Faulty NewOrderSingle

35=D|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|38=100|40=2|56=TARGET|
Missing: 11=ClOrdID, 44=Price

✓ Correct NewOrderSingle

35=D|11=ORDER12345|34=1|49=SENDER|52=20240101-10:00:00|54=1|55=AAPL|38=100|40=2|44=150.00|56=TARGET|
All required fields present

How FIX Doctor Helps

  • Automatically detects missing mandatory fields in NewOrderSingle messages
  • Highlights invalid enum values (e.g., Side=99)
  • Identifies missing Price for Limit orders
  • Validates message structure against FIX 4.2/4.4 specifications
  • Provides detailed error messages with suggested fixes
  • Shows timeline of all order-related messages

Diagnose NewOrderSingle errors instantly: Upload your FIX logs to FIX Doctor for automatic detection of missing fields and invalid values.

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