That could be issue with Rabbitmq connectivity. Check the nova-api logs and search with error keyword for better understanding. If the VM state in build Compute connectivity dropping is continue because of the Rabbit mq,
ERROR oslo_messaging._drivers.impl_rabbit [-] AMQP
That could be issue with Rabbitmq connectivity. Check the nova-api logs and search with error keyword for better understanding. If the VM state in build Compute connectivity dropping is continue because of the Rabbit mq,
ERROR oslo_messaging. _drivers. impl_rabbit [-] AMQP