An equipment failure at a shared banking computer centre in western Japan halted cash machines, branch counters and online banking at 128 regional banks on Friday 6 November.

The failure struck the West Japan Center of the Shinkin Joint System at about 1.30pm local time, the Shinkin Joint Center said. The system is the shared core platform used by 236 shinkin banks, more than 90 per cent of the sector, and the outage froze customer transactions at about 3,430 branches from the Tokai region westwards to Kyushu.

Customers could not withdraw cash, make deposits, transfer money or bank online for about five and a half hours before service was restored. Banks in eastern Japan, served by a separate centre, were unaffected, as were Japan's large city banks.

Shinkin banks are cooperative lenders serving local residents and small and medium-sized businesses, and the shared system lets them run their daily banking at lower cost. That centralisation also means a single failure can hit many separate institutions at once, and the outage left small firms unable to pay suppliers, settle invoices or run payroll for much of the afternoon.

No sign of a cyberattack

The operator said preliminary checks found no sign of unauthorised access, and the incident is being treated as an equipment failure rather than a cyberattack. Some reports linked the fault to communication equipment problems following an update to the ATM system in mid-October, but the organisation's official statement described it only as an equipment failure.

Engineers worked to restart the affected hardware and software, and the operator said it had notified all affected banks immediately. It has not yet given a definitive technical cause, and an investigation into the failure and measures to prevent a repeat is continuing.