Instance Migration Fails With Error "not able to execute ssh command: Unexpected error while running command.

Problem

Instance migration fails with the following erroron the source host.

None

973 INFO nova.compute.manager [req-[rUUID] [e-mail] admin] [instance: [UUID]] Setting instance back to ACTIVE after: Instance rollback performed due to: Resize error: not able to execute ssh command: Unexpected error while running command.Command: ssh -o BatchMode=yes A.B.C.D mkdir -p /pf9/instances/[UUID]Exit code: 255Stdout: u''Stderr: u"Warning: Permanently added 'A.B.C.D' (ECDSA) to the list of known hosts.\r<br>Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).\r<br>"

Environment

Platform9 Managed OpenStack - v3.6.0 and Higher

Cause

Password-less authentication is not configured between source and destination hosts.

Resolution

Set up password-less authentication between the current host and the new host as OpenStack requires a password-less authentication to copy the instance and the associated files to the destination host.