Hi, With Ussuri, failed to launch VM and saw such error from nova-compute. Didn't see any error in nova-api, nova-conductor and nova-scheduler. Did some search and not found any similar cases. Wondering anyone has ever hit this issue? ================================================= 2020-12-09 13:24:29.333 8 ERROR oslo.messaging._drivers.impl_rabbit [req-4226ac03-a5b7-446a-a74b-2785f9818927 - - - - -] [3830bc00-1541-4951-b4ed-e73faafaa78c] AMQP server on 10.6.20.21:5672 is unreachable: connection already closed. Trying again in 1 seconds.: amqp.exceptions.RecoverableConnectionError: connection already closed 2020-12-09 13:24:30.361 8 INFO oslo.messaging._drivers.impl_rabbit [req-4226ac03-a5b7-446a-a74b-2785f9818927 - - - - -] [3830bc00-1541-4951-b4ed-e73faafaa78c] Reconnected to AMQP server on 10.6.20.21:5672 via [amqp] client with port 55524. 2020-12-09 13:26:28.377 8 ERROR oslo.messaging._drivers.impl_rabbit [req-4226ac03-a5b7-446a-a74b-2785f9818927 - - - - -] Failed to publish message to topic 'scheduler_fanout': : amqp.exceptions.MessageNacked 2020-12-09 13:26:28.377 8 ERROR oslo.messaging._drivers.impl_rabbit [req-4226ac03-a5b7-446a-a74b-2785f9818927 - - - - -] Unable to connect to AMQP server on 10.6.20.21:5672 after inf tries: : amqp.exceptions.MessageNacked 2020-12-09 13:26:28.378 8 ERROR oslo_service.periodic_task [req-4226ac03-a5b7-446a-a74b-2785f9818927 - - - - -] Error during ComputeManager._sync_scheduler_instance_info: oslo_messaging.exceptions.MessageDeliveryFailure: Unable to connect to AMQP server on 10.6.20.21:5672 after inf tries: ================================================= Thanks! Tony