A technical breakdown caused angry passengers in the United Kingdom, because the British vaccination certificate app was down for a few hours. This meant that travelers could not take their flights.

The NHS health authority confirmed the technical problems. According to official information, it was not a question of refusals upon entry, but of refusing boarding. The background is that the data of the app could not be checked.

In general, it is highly recommended to always have a paper backup with you. This can be, for example, the printed vaccination or test certificate or the classic paper vaccination pass. Some countries officially only accept the QR code variant, but in the case of technical problems, one is usually accommodating if paper documents can be presented.