ISO 8583:1993 response code

904

Format error

Standard version: ISO 8583:1993
Paired version code: ISO 8583:1987 · 30

In ISO 8583:1993, response code 904 means “Format error”. It is paired here with ISO 8583:1987 response code 30, “Format error”. The reviewed dataset contains entries for Mastercard, Discover, and UnionPay; 2 of the five scheme columns remain N/A.

Merchant handling

Actions to be taken

Do not assume approval. Check the existing transaction status before correcting the request or retrying, so a late response does not create a duplicate authorization.

This is conservative merchant guidance derived from the published response meaning. Current scheme, acquirer, processor, merchant advice, and transaction-specific rules take precedence.

Scheme comparison

Descriptions in the reviewed sources

Each populated value links to its scheme record and preserves the raw code published by that source. N/A means no matching description exists in the reviewed public dataset.

Scheme descriptions compared with ISO 8583:1993 response code 904
Scheme	Raw code	Source description	Evidence
Visa	N/A	N/A	N/A
Mastercard	30	Format error	Official, limited scope
American Express	N/A	N/A	N/A
Discover	30	Format error	Secondary source
UnionPay	30	Message format error	Official, limited scope

Standard sources

Version and response-name evidence

ISO 8583:1993 metadataOfficial edition metadata; the full value table is not public.
ISO
Wikipedia ISO 8583 version tablesSecondary public source for the displayed response name.
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