We want to provide more information on this issue and progress toward resolution. At 5:18 AM PDT, we began experiencing increased API errors that originated from one of our EC2 sub-systems that is responsible for managing EC2 instances. This resulted in increased error rates for some EC2 APIs and affected new instance launches in a Single Availability Zone. The root cause of the error rates affecting the sub-system has been identified and engineers are currently working on resolving the issue. Existing instances remain unaffected by this issue.