A box must be specified.

hawksbill

$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
There are errors in the configuration of this machine. Please fix
the following errors and try again:

vm:
* A box must be specified.

The issue here is Vagrantfile config needs the section for config.vm.box

 config.vm.box = "packer_amazon-ebs_aws.box"    
	aws.region_config "us-west-2", ami: "ami-53ba502b"
        aws.security_groups = "default"
        aws.instance_type = "t2.micro"  
        aws.keypair_name = "...."  
        override.ssh.username = "ubuntu"  
        override.ssh.private_key_path = "..."