You can specify multiple zones and multiple instance types to improve the success rate of creating Elastic Container Instances (ECIs). The OperationDenied.NoStock error is returned when ECIs of the specified instance type are sold out in the specified region and zone. If you specify multiple zones and multiple instance types, ECIs of other instance types can be created or ECIs can be created in other zones. For more information, see Specify multiple instance types for creating an ECI.