Scheme code system · Mastercard
Official, limited scope91
Authorization system or issuer system inoperative
The issuer, authorization system, switch, or route is temporarily unavailable.
- Outcome
- Technical
- Code system
- Mastercard
- Raw format
- Two-character DE 39 response code
Operational context
Evaluate the advice code
For merchant-initiated transactions, evaluate DE 39 together with DE 48.84 Merchant Advice Code. MAC 02 means wait 24 hours; MAC 03 or 21 means do not retry.
Explicit mapping
SchemeLens concepts
These links are editorial mappings, not replacements for the raw source value. The relation shows how closely the wording aligns.
| Concept | Relation | Mapping note |
|---|---|---|
| Issuer or network unavailable | Direct semantic match | Mastercard wording mapped to the SchemeLens “Issuer or network unavailable” concept. |
Namespace check
The same raw value exists elsewhere
- Visa 91Issuer or switch inoperative
- Discover 91Authorization system or issuer system inoperative
- UnionPay 91Issuer is unavailable or unable to process
- EBANX 91Issuer or switch is unavailable
Provenance
Sources used for this record
- Mastercard: Transaction Processing RulesOfficial source for published DE 39 values and selected Merchant Advice Code rules; not a complete public technical specification.9 December 2025
SchemeLens keeps source wording, normalized concepts, and operational guidance separate so later evidence can be added without rewriting the raw record.