I am disabling ceilometer on my OpenStack Ocata cloud. As fas as I understand, besides stopping the ceilometer services, I can also apply the following changes to nova.conf on the compute nodes: instance_usage_audit = True --> false notify_on_state_change = vm_and_task_state --> None I have a problem with the latter change: # grep ^notify_on_state_change /etc/nova/nova.conf notify_on_state_change=None but in the nova log: 2019-01-21 08:31:48.246 6349 ERROR nova ConfigFileValueError: Value for option notify_on_state_change is not valid: Valid values are [None, vm_state, vm_and_task_state], but found 'None' I have also tried setting notify_on_state_change=<None> but it complains that it is not a valid value I can simply comment that line, but I am afraid there is a problem somewhere Thanks, Massimo