Technical Glitch Turns Into Brief Windfall for Customers of Irish Bank

For some customers at the Bank of Ireland, it was a windfall too good to be true.

The bank, one of Ireland’s largest, acknowledged on Wednesday that a “technical issue” with its online banking services had allowed some customers to withdraw more money than they had in their accounts, prompting the authorities to monitor crowds after long lines formed at some A.T. M.s around the country.

The problems began on Tuesday, after some Bank of Ireland customers complained that they could not…