"an authorized S3 team member using an established playbook executed a command which was intended to remove a small number of servers for one of the S3 subsystems that is used by the S3 billing process. Unfortunately, one of the inputs to the command was entered incorrectly and a larger set of servers was removed than intended... Removing a significant portion of the capacity caused each of these systems to require a full restart. While these subsystems were being restarted, S3 was unable to service requests..."
AWS says a typo caused the massive S3 failure this week | PCWorld
AWS cloudsplains what happened during S3 storage outage | TechCrunch
Massive Amazon cloud service outage disrupts sites
a more than four-hour problem... A big portion of Amazon Web Services' Amazon S3 system went offline Tuesday afternoon, a service used by 148,213 sites according to SimilarTech