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SchemeLens

ISO 8583:1987 response code

91

Issuer or switch is inoperative

Standard version
ISO 8583:1987
Paired version code
ISO 8583:1993 · 907

In ISO 8583:1987, response code 91 means “Issuer or switch is inoperative”. It is paired here with ISO 8583:1993 response code 907, “Card issuer or switch inoperative”. The reviewed dataset contains entries for Visa, Mastercard, Discover, and UnionPay; 1 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 8583:1987 response code 91
SchemeRaw codeSource descriptionEvidence
Visa91Issuer or switch inoperativeOfficial
Mastercard91Authorization system or issuer system inoperativeOfficial, limited scope
American ExpressN/AN/AN/A
Discover91Authorization system or issuer system inoperativeSecondary source
UnionPay91Issuer is unavailable or unable to processOfficial, limited scope

Standard sources

Version and response-name evidence