https://www.theverge.com/2018/6/2/17420666/visas-european-networks-back-up-and-running-hardware-failure

Yesterday, Visa experienced a widespread network failure in Europe, leaving many card holders unable to use their credit cards for purchases. Visa now says that it’s resolved the issue.

The outage was widespread, but not universal: users could still use their cards, but some major banks, such as Royal Bank of Scotland and the Bank of Ireland were affected. Customers could withdraw money from ATMs, but some retailers resorted to using paper slips to take down customer information. Visa says that the issue was the “result of a hardware failure within one of our European systems,” and that it wasn’t a cyberattack.