We recently migrated from Vault Ent to Vault CE (1.17.6). When running on Vault ENT we rarely ever saw the leader node change however since being on Vault CE we have seen the leader node change twice in few day period. When looking at the logs we noticed a pattern both times, almost right at the same time the leader node changes we see this error in the logs (note we actually see that error reported several times before the leadership changes):
# error message right before leader change
Mar 07 14:43:36 vault[10626]: \{"@level":"error","@message":"failed to revoke lease","@module":"expiration","@timestamp":"2025-03-07T14:43:36.990600Z","attempts":1,"error":"failed to revoke token: failed to revoke entry: failed to persist entry: node is not the leader","lease_id":"auth/approle/login/******","next_attempt":24601153282\}\
# next set of logs after above error
Mar 07 14:43:37 vault[10626]: \{"@level":"warn","@message":"heartbeat timeout reached, starting election","@module":"storage.raft","@timestamp":"2025-03-07T14:43:37.144778Z","last-leader-addr":"","last-leader-id":""\}\
Mar 07 14:43:37 vault[10626]: \{"@level":"info","@message":"entering leader state","@module":"storage.raft","@timestamp":"2025-03-07T14:43:37.516355Z","leader":\{\}\}\
Mar 07 14:43:40 vault[10626]: \{"@level":"info","@message":"entering follower state","@module":"storage.raft","@timestamp":"2025-03-07T14:43:40.279467Z","follower":\{\},"leader-address":"","leader-id":""\}\
Mar 07 14:43:41 vault[10626]: \{"@level":"error","@message":"failed to acquire lock","@module":"core","@timestamp":"2025-03-07T14:43:41.283351Z","error":"node is not the leader"\}\