In December, GitHub experienced no incidents that resulted in service downtime, marking a stable month in terms of availability. However, a follow-up investigation into an incident from November 27 revealed an edge case involving a large number of GitHub App token requests, which caused abnormal replication lag in a MySQL cluster affecting the GitHub Actions service. This led to some token requests failing due to outdated information in the database replicas. To prevent similar issues in the future, GitHub is updating its queries to manage the volume of token requests more effectively. The company continues to focus on enhancing its engineering systems and reliability, with more details available on their engineering blog.