UK supermarket Sainsbury's said that it would not be able to fulfill the "vast majority" of online deliveries on Saturday because of "technical issues."

The company said that the outage was "due to an error with an overnight software update."

A Sainsbury's refrigerated truck powered by a Dearman engine
Sainsbury's cancelled online orders after IT issues – Dearman

The delivery issue is compounded by the fact that the same system handles communications, so the company is unable to contact customers about the status of their orders.

In physical stores, the outage has caused problems with contactless payments. Customers can still use cash or chip and pin, but those who pay using their phones are unable to check out.

Sainsbury's apologized for the outage and said that it was working to resolve the issue and rebook new deliveries.

Update: Rival Tesco was also hit by a technical issue that affected a small proportion of its deliveries on Saturday.