NEW YORK (CNNMoney.com) -- A Wal-Mart Stores data system failure left shoppers unable to use some credit and debit cards on Thursday, a spokesman for the world's largest retailer said.
The outage lasted about 90 minutes at Wal-Mart and Sam's Club stores nationwide, and was caused by a failure of a back-up breaker while the main system underwent required maintenance.
"We apologize to any customers who were inconvenienced today, as we recognize electronic payment methods are very popular among our shoppers.
"Within a matter of minutes, we began making some changes to try and minimize the impact to our customers and allow most credit transactions to be processed. We were able to restore the system back to normal in approximately 90 minutes," Fogleman said.
Fogleman indicated that the system failure resulted in problems with card-reading machines.
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