Fastly has said a single customer caused yesterday’s outage, an outage that had widespread repercussions.

Fastly made headlines yesterday when an issue with the company’s network led to a major outage. As a content delivery network, some of the biggest companies in the world rely on Fastly, including Amazon, the BBC, CNN, Financial Times, The New York Times, Reddit, Spotify, GitHub, Twitch, Stack Overflow, Hulu, HBO Max, Quora, PayPal, Shopify, Stripe and Vimeo.

According to TheStreet, the company rolled out a software update in May that introduced a bug that could be triggered under very specific circumstances. The bug only needed a single customer to have a very specific configuration for the bug to active, which ultimately happened.

“Even though there were specific conditions that triggered this outage, we should have anticipated it,” the company said. “We apologize to our customers and those who rely on them for the outage and sincerely thank the community for its support.”