UPDATE 5PM: FRUSTRATED customers took to social media after being forced to abandon their groceries at Woolworths registers due to a national technical fault.
The outage has also shut down entire stores.
"Registers are offline so customers are standing in queues with baskets of food that they can't buy", she said.
A security guard was also stationed at the closed doors to turn shoppers away.
At 4.50pm, a Woolworths spokesperson confirmed via Twitter that their systems were back online.
Tyson Whelan, a journalism student at the Royal Melbourne Institute of Technology, said on Twitter a manager in East Doncaster, Victoria, told him "all the registers are out across the state".
Woolworths has apologised after a technical glitch knocked out thousands of registers across the nation for close to an hour, forcing some stores to shut.
"We apologise for the inconvenience this caused our customers", the spokesperson said.
Registers have shut down with stores unable to make sales.
Shortly after 4pm, the issue began affecting all registers across the country.
The spokeswoman did not say what caused the outage.
News Corp Australia has contacted Woolworths for comment.