VM Live Migration Fails with rsync "connection unexpectedly closed" After the Host root Password Is Rotated

Applicable Scenario

Use this article when a VM live migration on local storage fails with an rsync authentication error and the underlying cause is that the host's root password was changed outside of the ZStack platform. The validated fix is to update the new password in the ZStack UI so the management node can re-authenticate to the host.

• Product: ZStack Cloud.
• Version: 4.2.x~4.8.x.
• Component: Host agent and rsync over SSH.
• Trigger/Condition: Clusters where host root passwords are rotated outside the platform (e.g. by a host hardening script or a manual passwd change).

Problem Symptoms

• VM live migration fails. The UI error reads:

  Operation failed, because fail to migrate vm to host, because
  Warning: Permanently added '172.28.50.143' (ED25519) to the list of known hosts.
  rsync: connection unexpectedly closed (0 bytes received so far) [sender]
  rsync error: error in rsync protocol data stream (code 12) at io.c(226) [sender=3.1.2]