Courtney Rowe, a spokeswoman for the United States Department of Agriculture, emphasized that the failure was not related to the government shutdown.

Shoppers left carts of groceries behind at a packed Market Basket grocery store in Biddeford, Me., because they could not get their benefits, said Barbara Colman, a shopper from Saco, Me. The store manager posted a sign saying the system was not in use. Ms. Colman, who receives the benefits, said she had called toll-free telephone line for the program, which said the system was down for maintenance.

“That’s a problem,” Ms. Colman said. “You don’t want children going hungry tonight because of stupidity.”