Travel plans for millions of holidaymakers – and long-planned operations – were thrown into chaos across Europe by Friday’s IT outage.

Planes were unable to land or depart from Berlin airport for hours, train bookings were halted in Denmark and Germany’s leading IT security agency predicted that “we cannot reckon with a quick fix for this”.

Effectively cashless economies such as Sweden were badly hit by the software crash, with major regional retailers such as the Åhlens department store chain unable to process electronic payments.

Similarly, the southern German supermarket chain…