Cash registers at Target stores were refurbished after two hours of rest on Saturday, creating long queues at the counter for last-minute Father's Day customers.
The company attributed this failure to "an internal technology problem".
"Target's registries are fully online again and customers can buy their merchandise again in any store," retailer Jenna Reck said in a statement Saturday afternoon.
The problem was not about a security breach and no guest information was compromised, Reck said.
Some buyers have posted social network accounts on long lines before the problem is resolved. Cashiers were unable to digitize items or process transactions in certain stores.
Reports of long queues and registers sinking in places prey to Washington; Exton, Pennsylvania, Mays Landing, New Jersey; and Waxahachie, Texas.
Target quickly recognized the problems on Twitter, saying: "We are aware of a system problem in the store and we are working as fast as we can to solve it."
"We apologize for the inconvenience and frustration this has caused our customers," said Reck.
Michelle Acevedo and Associated Press contributed.