It means that you have CPUs with incompatible flags or you've got differing kernel versions that expose different flags or you've got differing libvirt versions that expose different flags. You either need to use a lowest common denominator cpu_model or do a cold migration.

From: Karera Tony <tonykarera@gmail.com>
Sent: 01 September 2023 10:13
To: openstack-discuss <openstack-discuss@lists.openstack.org>
Subject: Live migration error

CAUTION: This email originates from outside THG

Hello Team,

I am trying to migrate instances from one host to another but I am getting this error.

Error: Failed to live migrate instance to host "compute1". Details

Migration pre-check error: Unacceptable CPU info: CPU doesn't have compatibility. 0 Refer to http://libvirt.org/html/libvirt-libvirt-host.html#virCPUCompareResult (HTTP 400) (Request-ID: req-9dfdfe2e-70fa-481a-bd3d-c2c76a6e93da)

Any idea on how to fix this?

Regards

Tony Karera