More than two million people in Illinois use a so-called Link Card. That's one in six residents in the state. So when suddenly the system went down Saturday morning many customers just walked out of the store.
At a grocery store in Cicero, shopping carts full of food sat in the check-out area after being left there by customers unable to use their food stamp debit cards, including Link.
It was a similar story at a South Side Aldi, where a sign at the entrance spelled disappointment for many.
"Now I'm going to have to unfortunately do the fast food thing now. No cooking tonight," said Link Card user Rob Lee.
"That's how people starve," said shopper Sean Wright. "People starve if they don't have the Link to feed their children, to feed their family with."
By early afternoon, the Illinois Department of Human Services website had crashed as Link Card users tried to get answers.
Officials blamed it all on a technical problem at the Xerox Corporation, a private contractor, which in a statement said: "During a routine test of our back-up systems Saturday morning, Xerox's Electronic Benefits Transfer (EBT) system experienced a temporary shutdown."
The United State Department of Agriculture, which administers the food stamp program, said the problem is unrelated to the federal government shutdown.
But many had other opinions.
"I'm not surprised that they would say that this has nothing to do with the shutdown when everyone knows that it does," said Link Card user Durrell Featherstone. "No one buys it."
"I don't know. So much has been going on with this government shutdown, you know. Not sure," said Rosita Gaujean.
That skepticism isn't lost on Joe Mengoni, who runs dozens of group homes for residents with developmental disabilities.
"My first reaction was the federal government shutdown. And I thought this has to be tied into that somehow," he said.
Those homes depend on food stamp benefits.
"I would love for the state of Illinois to say, you know, 'We have enough in reserves to cover you through the end of the month, and if the shutdown continues, then we need to look at plan B,'" Mengoni said.
Late Saturday night, Xerox and state officials said the problem had finally been resolved but a number of stores contacted said their Link system remained down.