A technical problem during a routine update of back-office files prevented some customers at Tesco Bank from being able to see online accounts for two days.
The bank announced on Twitter that the problems which began on the morning of Tuesday 3 February 2015 were fixed by the following Thursday morning.
“Customers can now see their accounts online as normal. We apologise for any inconvenience caused and thank customers for their patience,” said the Twitter announcement.
The bank did not reveal the actual problem but a Tesco Bank spokesperson told Computer Weekly that it occurred during a daily IT update.
“Every night we automatically update our back-office files," said the spokesperson. "During an update on Tuesday morning, a technical issue led to a small proportion of customers being unable to see their accounts in online banking.
"We worked hard to resolve this issue and all customers could see their accounts as normal by 6am on Thursday morning. While customers were still able to use their accounts and contact us by phone, we recognise that this will have been an inconvenience for those affected and we apologise for that.”
More on banking IT
Reports suggested about 300,000 people could not see their accounts during the problem.
Tesco is one of a group of companies trying to challenge the traditional banks. One of the perceived advantages for these new banks is IT.
The retailer set up its own core banking system in November 2009, when it selected an off-the-shelf system from Fiserv. Before that it shared systems with the Royal Bank of Scotland.
In January 2015, Sainsbury's Bank – another challenger bank – experienced IT problems that left customers unable to use their credit cards for a day.
Customer cards were declined at checkouts and customers were advised to contact the bank.