Between 20:02 UTC and 20:10 UTC on September 17, 2026, a problem at multiple card issuers in Italy caused Mastercard and Visa 3D Secure (3DS) authentications to return a status of U (Unavailable). The issue is now resolved.
What happened
On September 17, 2026, multiple card issuers in Italy became unavailable to respond to 3DS authentication requests for both Mastercard and Visa at the same time. Checkout.com returned a 3DS status of U (Unavailable) for the authentications routed to those issuers, because the issuers did not respond.
The cause was on the card issuer side. None of our systems were at fault, and authentications routed to issuers outside Italy were not affected.
In total, 719 authentications were affected across 70 merchants before the issuers restored normal service.
What you saw
Affected authentications returned a 3DS status of U (Unavailable). This status means the card issuer was unavailable to respond to the authentication request, so the authentication did not complete.
What you need to do
The issuers have restored normal service, so you can retry any affected payment as a new payment and expect it to process as usual.
If you want to confirm which of your payments were affected, contact your account manager or request support.