Hey all, Just wanted to give everyone a heads up about a recent change [1] in behavior for the resize [2] and migrate [3] server action APIs: https://docs.openstack.org/releasenotes/nova/unreleased.html#other-notes The scheduling step for resize and migrate has been changed from synchronous to asynchronous, so users will no longer receive a 400 error for NoValidHost. To discover whether the resize or migrate has failed during scheduling, users must use the server actions API [4], which is called "server events" in the openstackclient [5]. There is a WIP proposal [6] to add exception messages to events in the server actions API: https://review.opendev.org/694428 in order to communicate additional failure info to non-admin users. I think we'll want this as the server actions API becomes more of a source of information for the end user. Feel free reply here or visit the review to add your thoughts. Cheers, -melanie [1] https://review.opendev.org/693937 [2] https://docs.openstack.org/api-ref/compute/#resize-server-resize-action [3] https://docs.openstack.org/api-ref/compute/#migrate-server-migrate-action [4] https://docs.openstack.org/api-ref/compute/#servers-actions-servers-os-instance-actions [5] https://docs.openstack.org/python-openstackclient/latest/cli/command-objects/server-event.html [6] background: http://lists.openstack.org/pipermail/openstack-discuss/2019-November/010775.html