A week and a half after the supermarket went offline, the deliveries still have not restarted

The shops stayed open. The tills kept working. Almost everything else went dark. Ahold Delhaize spotted suspicious activity in its network on 12 October and took systems offline as a precaution, which was the right call and also an expensive one. Albert Heijn's website, app and home delivery service stopped. So did Etos and Gall and Gall. In Belgium, Delhaize. In the United States, Stop and Shop, Giant Food, Hannaford and Food Lion lost their sites, and staff reported trouble reaching their own schedules and pay details. Distribution centres shut, which emptied shelves. Bonus card discounts and app savings simply stopped applying. Dutch estimates put the damage above 10 million euros.

Chief executive Frans Muller said taking systems offline "was a precautionary measure that affected most of our brands across Europe and the United States". The company reported the incident to Dutch police on 19 October, after some prodding, having already notified the national cybersecurity centre. It says the investigation has so far found no evidence that customer, employee or partner data was stolen. Online deliveries were not expected to resume before 23 October, which would make eleven days.

One thing to keep separate: the attack on refrigeration controllers in French supermarkets happened in the same fortnight, and Dutch authorities say they have no reason to believe the two are connected. If you shop with any of these brands, expect the gap to be filled with fake "your order was cancelled, confirm your refund" messages. The chains are not emailing anyone about refunds, and no genuine refund ever needs your card number.

The household version of the same lesson is keeping your own copy of what matters before a system goes down, which is what Tendvane's one-click backup of Documents, Pictures and Desktop is for.