Two of the UK’s biggest supermarket chains – Tesco and Sainsbury’s – were hit with technical issues on Saturday.
Sainsbury’s customers were unable to make contactless payments following an overnight software update and the firm was not able to fulfil the “vast majority” of online deliveries.
Meanwhile, Tesco had to cancel some online orders that were due for delivery.
Both chains apologised to customers and later said the unrelated issues were resolved.
Sainsbury’s had said it could not deliver most online grocery orders and was unable to contact customers directly.
A spokesperson later said: “We can confirm that contactless payments are now back up and running in all stores, alongside all other forms of payment.
“Our Groceries Online ordering system is working as normal and customers can place an order for delivery any time from tomorrow.
“We apologise to customers for the inconvenience caused by technical issues today – thank you for bearing with us.”
One customer said she was meant to have a “very important” order delivered between 8-9am, which did not happen.
Yvonne, 56, from the Reading area, said: “The main issue I have with this is the poor communication from Sainsbury’s to its customers.
“It was obvious something was wrong at 7am as that’s when they send the receipts normally.
“Couldn’t get through to anyone about my 8 to 9 delivery.
“No statement until about 8.30, only seemed to be on social media which not all customers will have.
“Should have been an email or text to customers which would have helped those like myself expecting an early morning delivery. Much to improve on with their communications.”
Argos, which is owned by Sainsbury’s, was also affected by the software update, meaning some customers may have had issues ordering new items or collecting orders in-store.
It said there may have been delays in fulfilling orders placed.
Only a small proportion of Tesco orders due for delivery on Saturday were impacted, it is understood.
Tesco customers received an email if their order was disrupted, and if it was cancelled they were not charged.
In-store shopping and placing orders on the app and website are not believed to have been affected.
Tesco said: “The vast majority of our online orders are being delivered as normal, but due to a technical issue earlier today we have had to cancel a small number of orders.
“We are contacting affected customers directly, and we’re really sorry for the inconvenience.”