Going Global Locks In More Than Topology: Version Lockstep and the Features That Turn Off

Attaching a second Region converts your Aurora cluster from an independent unit into a member of a global cluster — and the global cluster becomes the unit of operation. Engine versions must stay in lockstep: managed cross-region switchovers and failovers require the same major and minor versions, and for Aurora MySQL no minor version tolerates differing patch levels at all. Automatic minor version upgrades silently stop applying — the setting exists but has no effect. A list of single-region features turn off at the boundary: Backtracking, Secrets Manager integration, Aurora Auto Scaling on secondary clusters, per-cluster stop/start, and renaming member clusters.

The trap isn't a failed attach — it's month six. An emergency cross-region failover is needed, patch levels have drifted because auto minor upgrades were a no-op and nobody ran coordinated patching, so the managed failover path is unavailable and the manual path (detach to standalone, then rebuild the topology region by region) becomes the incident plan. Or a team carries single-region operational assumptions into the global world — "we can Backtrack the bad UPDATE" — and discovers the option no longer exists.