In a letter to the UK‘s Treasury Select committee chair Nikky Morgan, Visa’s Europe chief executive, Charlotte Hogg, said that more than 5 million transactions failed during their 10-hour outage earlier this month.
The service failure started on Friday at 2.35pm and was not completely fixed until 12.45am the following day.
The letter also revealed that about 10% of the 51.2 million transactions in Europe were affected by the outrage. In the UK, 2.4 million transactions failed, with 1.7 million credit and debit cards affected.
According to Hogg, a hardware component in Visa‘s primary data centre “suffered a very rare partial failure”, and Visa’s secondary data centre failed to kick in automatically to process the transactions.
“As a result, it took far longer than expected to isolate the primary site; in the interim, the malfunctioning system at the primary data centre continued to try to synchronize messages with the secondary site. This created a backlog of messages at the secondary data centre, which, in turn, slowed down that site’s ability to process incoming transactions,” explains Hoggs.
Visa looks safe from further action from UK politicians, as they are “satisfied” by Hogg’s letter.