A botched update mixed up transaction data across accounts, with thousands now receiving goodwill payouts

A botched overnight software update at Lloyds Banking Group left up to 447,000 customers briefly seeing other people's transactions in its mobile apps, with the bank now acknowledging the scale of the incident and compensating affected users.

Details of the incident emerged in a letter from Jasjyot Singh, the bank's CEO of consumer relationships, to the Treasury Committee, following questions about the March 12 glitch that affected Lloyds, Halifax, and Bank of Scotland users.

According to Singh, the issue was triggered by an IT change pushed overnight between March 11 and 12, introducing a software defect in the API handling transaction data. Between 03:28 and 08:08 that morning, customers logging into the apps could end up seeing fragments of other people's account activity if they accessed their transaction lists at almost exactly the same moment as another user.

Lloyds says no one could move ...