An unprecedented Amazon Web Services outage that caused nearly 150 major sites and apps – including Snapchat, Venmo and Roblox – to go dark was apparently caused by a common tech glitch. The 15-hour outage appeared to be caused by an “underlying DNS issue,” Amazon Web Services said in a status tracker on its website.

The global AWS outage is affecting popular services like Fortnite, Roblox, Snapchat, and Alexa, leaving millions of people around the world disconnected.

From Reddit and Snapchat to Delta and Zoom, more than a thousand websites around the globe were knocked offline early Monday—and continued to have problems into the afternoon—after a major outage at Amazon Web Services,

The cloud-computing division of the internet giant is used by thousands of internet customers, many of whom reported disruptions on Monday.