Photos show the chaos behind the global IT outage that's impacting retailers, flights, and hospitals

European airlines Ryanair and KLM are also among those to be impacted by the outage.

Edinburgh Airport in the UK and Berlin Airport in Germany have warned of delays.

A spokesperson for Singapore's Changi Airport told BI: "Due to a global outage affecting IT systems of many organizations, the check-in process for some airlines at Changi Airport is being managed manually."

This included the "issuance of boarding passes," the spokesperson said.

Local media reports also showed long lines at Changi Airport's check-in counters.

Major UK airports, Heathrow, Gatwick, and Luton, have all been affected.

At Luton Airport, near London, Nick Xydias told Business Insider he was stuck waiting for a Wizz Air flight to Larnaca, Cyprus.

"It's my birthday, and we'd booked a romantic trip with my wife. She'd got a new dress and everything," he told Business Insider from a winding and frustrated line of passengers on Friday morning.

Luton staff later wrote on X that some flights were affected but that the airport was still operating.

Ryanair, Europe's largest airline, warned of "disruption across the network due to a Global 3rd party IT outage which is out of our control" and is advising passengers to head to the airport early.

A passenger at the Rajiv Gandhi International Airport in Hyderabad wrote on X that he had been issued a hand-written boarding pass by Indian airline IndiGo.

Business Insider was unable to verify his account. However, IndiGo confirmed on X that its booking, check-in, and access to boarding cards process was impacted by the outage.

Australian grocery store chain Woolworths told BI that some stores had "been impacted as a result of the global IT issue." However, all but six stores were open, while some had fewer checkouts functioning.

A banner on Woolworths' website as of Friday said that it's "experiencing intermittent technical difficulties instore and online."

Social media users said Waitrose, an upmarket UK grocery store chain, was only taking cash payments because card machines weren't working.

Sky News has been showing archive footage and briefly displayed an error message.

The news site appears to be up and running at the time of writing.