etcd Blog
Avoiding Zombie Cluster Members When Upgrading to etcd v3.6
Summary: SIG-etcd has patched another potential issue blocking upgrades from v3.5 to v3.6. If you are upgrading, make sure to update to v3.5.26 or later first.
Issue Summary
Recently, the etcd community addressed an issue that may appear when users upgrade from v3.5 to v3.6. This bug can cause the cluster to report “zombie members”, which are etcd nodes that were removed from the database cluster some time ago, and are re-appearing and joining database consensus. The etcd cluster is then inoperable until these zombie members are removed.
Follow Up - Preventing Upgrade Failures from etcd v3.5 to v3.6
We have identified and fixed an additional scenario that may cause upgrade failures when moving from etcd v3.5 to v3.6. This post contains details, the fix, and additional workarounds. Please refer to issue 20793 to get detailed technical information.
Issue
In a previous post — How to Prevent a Common Failure when Upgrading etcd v3.5 to v3.6 — we described an upgrade issue affecting etcd versions in v3.5.1-v3.5.19. That issue was addressed in v3.5.20. However, a follow-up investigation revealed that the original fix did not cover all scenarios.