The Day Facebook Disappeared – Global Outage (2021)
In October 2021, Facebook, Instagram, WhatsApp, and Messenger experienced a global outage lasting approximately six hours. The disruption was caused by a configuration change that severed Facebook's servers from the internet, affecting billions of users worldwide.
Background
- On October 4, 2021, Facebook (along with Instagram, WhatsApp, Messenger, and Oculus) went offline globally for roughly 6–7 hours.
- The cause was a misconfiguration in Facebook's Border Gateway Protocol (BGP) updates — the system that directs internet traffic to the right servers. An engineer error during a routine maintenance command effectively erased the routes that tell the internet where Facebook's servers are.
- Because Facebook's internal systems (badges, DNS, even the tools needed to fix the outage) depended on the same network that went down, engineers couldn't easily access the affected data centers to roll back the change.
- The outage was notable for its scale: it took down a platform used by nearly 3 billion people and disrupted businesses, login systems (many sites use "Login with Facebook"), and even Facebook employees' own work tools.
- It also fueled debates about internet centralization — a single company's configuration error made a huge chunk of the web unreachable for hours.