FIX Error: Invalid Tag Value – Causes and Fixes
An invalid tag value error occurs when a tag's value doesn't match the expected format, data type, or enum values defined in the FIX specification. Examples include: non-numeric value in numeric field, invalid enum (e.g., Side=3 when only 1,2 are valid), out-of-range numbers, or incorrect timestamp format.
Root Cause
1) Data type mismatch (string in numeric field), 2) Invalid enum value, 3) Out-of-range values (negative price, zero quantity), 4) Incorrect format (timestamp, date), 5) Encoding issues (non-ASCII in text field).
Broker/Exchange Action
Broker rejects with SessionRejectReason=10 (Value is incorrect) or 11 (Incorrect data format). RefTagID points to the problematic tag.
Client/Your Action
1) Validate tag values against FIX spec before sending, 2) Check enum values are valid, 3) Ensure numeric fields are numbers, 4) Validate timestamp formats (YYYYMMDD-HH:MM:SS), 5) Use FIX validation libraries.
Example FIX Message
How FIX Doctor Detects This
FIX Doctor validates common tag values (Side, OrdType, OrdStatus) and flags invalid enums or formats. Errors appear with the specific tag and suggested valid values.
Related Errors
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