Outage in Fat Zebra
Errors affecting Merchants acquiring via Fiserv (First Data)
Resolved MajorIncident Report
We are currently investigating a problem with merchants acquiring via Fiserv (First Data), receiving '91 - Host or Switch Unavailable' responses for some transactions.
Components affected
Fat Zebra Gateway: Fiserv XTPTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
RESOLVED
22 days ago - at 08/25/2026 11:59PM
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.
IDENTIFIED
22 days ago - at 08/25/2026 09:50PM
Fiserv has confirmed they are currently investigating a service disruption to Mastercard Transaction Processing on their side.
INVESTIGATING
22 days ago - at 08/25/2026 09:48PM
We are currently investigating a problem with merchants acquiring via Fiserv (First Data), receiving '91 - Host or Switch Unavailable' responses for some transactions.
Latest Fat Zebra outages
Payment failures with Mastercard cards - about 1 month ago
Gateway transactions timing out - about 2 months ago
Downstream issues with EFTPOS - 3 months ago
Transaction time outs - 4 months ago
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