NEW YORK -- Macy's has resolved an issue in its credit card system which slowed transactions nationwide on Black Friday, a company representative said.
The Macy's representative said the delays were caused by "a capacity-related issue" and apologized to customers for any inconvenience.
Users on Twitter complained of issues when trying to purchase items.
"Sorry shoppers! macys.com is temporarily closed for scheduled site improvements as we work to bring you a better shopping experience," one Twitter user posted a screenshot of an error message he received on the site.
".@Macys credit card system down nationwide. They are not informing shoppers standing in long lines. Getting ugly out there," another user wrote.
Another customer said she left $300 worth of items on the counter due to credit card machines being down.
Macy's acknowledged an issue, but seemed to downplay the impact.
"It is taking longer than usual to process some credit and gift cards in our stores," a spokesperson told CNNMoney. "But we have added additional associates to the floor who are working to resolve the issue as quickly as possible."
The issue comes at an inopportune time for the company. Its sales continue to tumble as Americans largely shun the mall. Macy's revenue dropped 6.1% in its most recent quarter, which marked the 11th straight quarterly decline.
Like other brick-and-mortar retailers, Macy's is struggling as consumers opt to shop on Amazon and other websites.
Earlier today, Lowe's website experienced outages.
Macy's website also crashed on Black Friday last year. In 2015, Target's website experienced issues on Cyber Monday.
ABC7 Chicago contributed to this report.
CNNMoney's Matt Egan contributed to this report.
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Macy's Black Friday stalled by problems with credit card system