FIX Doctorsupport@fixdoctor.tech

FIX Error Tag 371: Tag missing

What this error means

Tag 371 (RefTagID) in a FIX Reject message indicates that the original message was rejected because a specific tag was missing. When RefTagID=371 appears in a reject, it means tag 371 itself was missing, but more commonly, RefTagID points to another missing tag (like 11 for ClOrdID). Tag 371 is used to reference which tag caused the rejection.

Common causes

  • The most common causes are:

  • 1) Application logic fails to populate required tags before sending the message,

  • 2) Message construction library omits mandatory fields,

  • 3) Field filtering removes required tags incorrectly,

  • 4) Message validation passes but field is empty or null,

  • 5) FIX version mismatch where different tags are required.

Example log snippet

8=FIX.4.4|9=123|35=3|49=EXCHANGE|56=CLIENT|34=5|52=20231116-10:30:00|371=11|372=D|373=6|58=Required tag missing: ClOrdID|10=123|

How to fix it

1) Review the RefTagID value in the reject message to identify which tag is missing 2) Verify all mandatory tags are populated per FIX specification for your message type 3) Ensure message construction includes all required fields 4) Check that no field filtering removes mandatory tags 5) Validate message completeness before sending 6) Review FIX version requirements - different versions may require different tags

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