An outage of several hours of the NHS app caused chaos for travellers at airports and ferry terminals.
They were unable to prove their vaccine status via the app with many blocked from boarding flights.
The app went down for more than four hours.
When functioning, the NHS Covid Pass can show proof of vaccination and current test results.
NHS Digital said the outage was due to ‘a technical issue with a global service provider that affected many different organisations.’
"Following an urgent investigation, this has been fixed," a NHS spokesperson said.
It led to many angry travellers missing their flights, while some were forced to pay for new flights.
Earlier this month, Scotland’s new Covid vaccine passport app also experienced an outage.
