Macy's confirmed on Friday it was having trouble with its credit card systems on one of the busiest and most important shopping days of the season. That trouble was resolved by Friday evening.

"We have fully resolved today's system issues. We highly value our customers and sincerely apologize for any inconvenience today's system slowdown may have caused during their shopping experience," a spokesperson for the company said.

The retailer attributed the processing "delays" to "a capacity-related issue."

Word began percolating on social media around noon ET on Friday from shoppers across the country.

"Hey Macys, just left $300 of items on counter because your credit card machines are down at State St Chicago," wrote Meghan McCollough.

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The retailer began responding to complaints on social media a little after 1:00 p.m. ET, asking users having trouble to direct message it.

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Around the same time, Macy's said in a statement and message to frustrated shoppers it was having a slowdown in processing payments. Customers said the system wasn't working at all.

Shoppers trying to place orders on Macy's website received the following message: "We're unable to verify availability of some item(s) in your order. Place your order now, and we'll send you an email confirming availability and shipping when our system is back online, or please try again later."

Macy's needs a strong holiday season. The retailer has suffered 11 straight quarters of same-store sales declines as shopping habits have changed, moving both online and away from clothes. Last year, Macy's generated roughly 33 percent of its revenue in the fourth quarter.

Even if the company fixes its issues Friday, the impact may linger throughout the shopping season, said Paul Argenti, a professor of corporate communications at Dartmouth's Tuck School of Business. For customers that are not particularly loyal to the retailer, a bad experience on Black Friday may turn them off throughout the holidays. Macy's is not known to have as loyal a customer base as competitor Nordstrom, Argenti said.

"I can't think of anybody that needs this less than Macy's," he said.

The day had started off well for the retailer and many of its peers. Consumer confidence seems have to propelled this shopping season to one of the strongest in years. The National Retail Federation has forecast total holiday retail sales to climb 3.6 to 4 percent in 2017.

Macy's has been eager to use the holiday season as a chance to test the impact of some of the in-store investments it has made over the past year. These include a partnership with Samsung and expanding its private label brands business.

The department store also recently revamped its loyalty program, offering discounts and perks like free shipping and priority customer service based on how much they spend at the retailer.

Macy's CEO Jeff Gennette highlighted some of these investments Friday morning in a conversation with CNBC. Optimism regarding the department store's outlook, along with what appears to be a strong Black Friday, buttressed up Macy's stock. Its shares were up as much as 4 percent in the morning, before closing up 2 percent.

—CNBC's Courtney Reagan and Amanda Lasky contributed to this report.