Facebook’s most severe outage ever is reportedly due to database problems. The BBC reports that the only comparable Facebook outage was in 2008, when the site had 150 million users rather than the 2.3 billion monthly users it has today. Facebook, Messenger, WhatsApp, and Instagram were all affected—though Instagram announced that it was back by posting an Oprah GIF in the early hours of Thursday. Facebook hasn’t confirmed the what the problem was, but NBC Bay Area anchor Raj Mathai reported late Wednesday that the issue was to do with the company’s databases, which a source told him were “overloaded.” Mathai’s internal Facebook source told him: “We are racing to spin up new machines as others go down. Mostly resolved... but it takes time.” Facebook did confirm the outages were not a result of a Distributed Denial of Service attack, known as DDoS—a cyberattack that floods its target with extremely high volumes of traffic.