Some customers at one of Ireland’s largest banks, for one feverish summer evening, happened upon what seemed to be a magical loophole: They could spend their cash and apparently save it, too.
When a “technical issue” at Bank of Ireland cut some customers off from online banking services on Tuesday, others found that it also allowed them to transfer or withdraw funds, even beyond the account limit, without changing the reported balance.
It was an apparent windfall that brought lines to some A.T.M.s across the country, and in turn prompted the authorities to monitor crowds, even as the bank warned people not to overdraw their accounts.
There was an “unusual volume of activity” at several machines in Dublin and elsewhere, the Irish police, An Garda Síochána, said. They added that officers were deployed to provide security near some of the machines for what they said were public safety and order reasons.
“We are aware that the technical issue meant some customers were able to withdraw or transfer funds above their normal limits,” the bank said in a statement on Wednesday apologizing for the outages.
Services were restored overnight, but customers were warned that online services would be slow on Wednesday as the bank caught up with processing payments, the bank’s customer support representatives said on X, the social media platform formerly known as Twitter.
And they were clear that any money transferred from the account was not free to keep. Transfers and withdrawals made during the disruption would appear on accounts that day, the bank said in its statement, adding: “We urge any customer who may find themselves in financial difficulty due to overdrawing on their account to contact us.”
But on Wednesday, customers still flooded the social media account with angry messages, reporting that their balances had not been updated correctly or that their online banking services remained disrupted.
Some users said they could not verify that monthly rent or mortgage payments had cleared, and others complained that they were scared to spend in case they accidentally went into overdraft, or that they were having trouble reaching support services to discuss a repayment plan.
The technical issues, according to local media outlets, meant that some customers were able to transfer large amounts — some reports put the figure at 1,000 euros, or about $1,092 — to an account with another bank, without their Bank of Ireland balances recording the transaction, and then withdraw the amount in cash.
In an apparent nod to the reports, the Irish police reminded people of their “personal responsibility” for their finances.
Aside from the withdrawal glitch, customers said that the outage was especially frustrating given that the bank charged monthly fees to maintain the account — 6 euros for a personal use account — and called for a reimbursement.
The episode was serious enough that government officials asked the Central Bank of Ireland, the industry regulator, to investigate the circumstances leading to the glitch.
“Disruption to banking services can have a significant effect on people’s personal lives and on the running of businesses,” Michael McGrath, Ireland’s finance minister, said in a statement.
Given the country’s “growing dependence on technology for the delivery of financial services,” Mr. McGrath said, he had also asked the central bank to more broadly assess the robustness of technology systems used by regulated banks in Ireland to cushion the impact of outages.
A spokesman for the Central Bank of Ireland said in a statement that it was monitoring the situation and was in contact with Bank of Ireland.
In its apology, Bank of Ireland acknowledged the service “fell far below the standards our customers expect from us.”
Headquartered in Dublin, Bank of Ireland is among the oldest financial institutions in the country, and opened Ireland’s first A.T.M. in 1980.