Hi, In a prototype, we have improved Nova's scheduling error messages. This helps both developers and end users better understand the scheduler problems that occur on creation of an instance. When a scheduler error happens during instance creation via the nova upstream, we get the following message on the Overview tab (Horizon dashboard): "No valid host was found." This doesn't give us enough information about what really happened, so our solution was to add more details on the instance's overview page, e.g.: **Fault:Message** attribute provides a summary of why each host can not satisfy the instance’s resource requirements, e.g. for controller-0, it indicates “No valid host was found. Not enough host cell CPUs to fit instance cell” (where cell is a numa-node or socket). **Fault:Details** attribute provides even more detail for each individual host, for example it shows that the instance “required” 2 CPU cores and shows the “actual” CPU cores available on each “numa” node: “actual:0, numa:1” and “actual:1, numa:0”. These details are also present using the OpenStack CLI, in the _fault_ attribute: - openstack server show <instance> With that in mind, we'd like to know if you are open to consider such a change. We are willing to submit a spec and upstream that implementation. Regards, - nicodemos