A technical problem at payments company Opayo that left many retail outlets around the country unable to process card transactions has been resolved.
The issues emerged around lunchtime today and continued to persist late into this evening.
The outage hit point of sale terminals and led to card payments being declined.
Opayo has around 50,000 customers in Ireland, although not all were impacted by the problem the firm said.
Angry customers took to social media to complain that it was taking so long for a resolution to be found.
Shoppers who contacted RTÉ News said they had been unable to use their cards to pay for items in supermarkets and convenience stores.
However, in an update posted on its website just before 11pm tonight, Opayo said the problem had been fixed and the system is functioning normally again.
"We can confirm the issue is now resolved and normal service is restored. We continue to monitor the service closely," it said.
"Thank you for your patience during this service interruption to your business, for which we again apologise."
Opayo was formerly called Sage Pay, but the name was changed after Sage Pay was bought by US Bancorp subsidiary Elavon in 2019 for a reported €270m.
Today's problems did not impact Opayo's online payment services, the company said, although some SuperValu customers reported problems carrying out online transactions on the supermarket's website.
In a tweet, SuperValu confirmed earlier that its card payment service provider was experiencing technical issues which were affecting the processing of card payments at its stores as well as online.
"Our provider is working to rectify the issue and to ensure the affected card payment systems will be back working as soon as possible," it said.
"Customers can pay in cash in stores, as normal, and we apologise to them for any inconvenience caused."
