Amazon RDS for MySQL 8.0 reaches end of standard support on July 31, 2026. This guide covers three upgrade paths to MySQL 8.4: in-place upgrade (simplest, minutes-to-hours downtime), Blue/Green Deployment (under 5 seconds switchover, best for production), and snapshot restore (best for dev/test). Key breaking changes in 8.4 include mysql_native_password being disabled by default in favor of caching_sha2_password, removal of MASTER/SLAVE terminology, and InnoDB variable default changes. RDS runs mandatory prechecks automatically before upgrading, generating a PrePatchCompatibility.log if incompatibilities are found. Extended Support is available post-deadline at per-vCPU hourly rates, doubling for Multi-AZ deployments. Best practices include testing on non-production first, creating a mysql8.4 parameter group, upgrading read replicas before the primary, taking manual snapshots, and warming the buffer pool after upgrade.
