“We are investigating the issue and will update as soon as we can.”
The pass is usually used for overseas travel or attending certain events in England.
Social media users expressed their worries online, asking how long it might take for the issue to be fixed.
One wrote: “Due to travel in four hours time but won’t be if the app isn’t working again.”
The digital version of the Covid pass is only for those over the age of 16 who are vaccinated in England, Wales or the Isle of Man.