Fat Zebra incident
Errors affecting Merchants acquiring via Fiserv (First Data)
Resolved after 2 hours 11 minutes, affecting Gateway: Fiserv XTP, on August 25, 2026.
Please see a further update from Fiserv below: Fiserv would like to advise clients and partners that the issue impacting Mastercard transaction processing has now been resolved. Mastercard transactions are now processing as expected.
Affected components
Update timeline
- investigating Aug 25, 2026, 09:48 PM UTC
We are currently investigating a problem with merchants acquiring via Fiserv (First Data), receiving '91 - Host or Switch Unavailable' responses for some transactions.
- identified Aug 25, 2026, 09:50 PM UTC
Fiserv has confirmed they are currently investigating a service disruption to Mastercard Transaction Processing on their side.
- resolved Aug 25, 2026, 11:59 PM UTC
Please see a further update from Fiserv below: Fiserv would like to advise clients and partners that the issue impacting Mastercard transaction processing has now been resolved. Mastercard transactions are now processing as expected.
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