Target customers Sunday reported issues checking out at stores across the country, after registers were down for nearly two hours Saturday due to a system outage that created long lines.
Customers said card readers weren't working and they had to pay in cash.
In a statement to CNBC, a Target spokesperson said the company's payment processor, NCR, experienced issues at one of its data centers. As a consequence, Target was unable to process card payments at some stores for about 90 minutes.
The spokesperson said the issue was not security related and was not connected to the outage on Saturday. The issue has since been resolved and payments are being processed normally, according to Target.
"Although this was unrelated to Saturday's issue, we know many guests had a frustrating shopping experience in our stores this weekend," the spokesperson said. "For that, we are truly sorry. We never want to disappoint any guests and we're working tirelessly to ensure these issues don't happen again."
NCR could not be immediately reached for comment.
Registers at Target stores were down for about two hours on Saturday due to what Target described as an "internal technology issue" that was not security related.
Customers expressed their frustrations on Twitter Sunday.