More than 1,000 companies had 6.5 million reports of disruption, including Snapchat, Reddit, Roblox and Lloyds bank.

Amazon Web Services, a major provider of cloud hosting that underpins much of the web and everyday online tools, went offline because of a problem with one its core database products.

Technology has delivered groundbreaking advances in recent decades—from life-saving medical treatments to the everyday convenience of carrying a powerful computer in a pocket. Yet despite the rapid ...