Vagrant up error /sbin/ifdown eth1 2> /dev/null - vagrant

Question

on ubuntu16x64 + virtualbox + vagrant
I'm trying add the laravel/homestead box
I get error in
$ Vagrant up
$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'laravel/homestead'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'laravel/homestead' is up to date...
==> default: Setting the name of the VM: homestead-7
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
default: Adapter 1: nat
default: Adapter 2: hostonly
==> default: Forwarding ports...
default: 80 (guest) => 8000 (host) (adapter 1)
default: 443 (guest) => 44300 (host) (adapter 1)
default: 3306 (guest) => 33060 (host) (adapter 1)
default: 5432 (guest) => 54320 (host) (adapter 1)
default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
default: SSH address: 127.0.0.1:2222
default: SSH username: vagrant
default: SSH auth method: private key
default:
default: Vagrant insecure key detected. Vagrant will automatically replace
default: this with a newly generated keypair for better security.
default:
default: Inserting generated public key within guest...
default: Removing insecure key from the guest if it's present...
default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
==> default: Setting hostname...
==> default: Configuring and enabling network interfaces...
The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
/sbin/ifdown eth1 2> /dev/null
Stdout from the command:
Stderr from the command:
the output refers to a problem with the generated keys
I am not familiar with the key generation, so perhaps the problem is there, I report the steps I did to create them, maybe I made some big stupid
$ cd /home/ubiagio/.ssh/
$ ssh-keygen -t rsa -C biagiopas#yahoo.it
Generating public/private rsa key pair.
Enter file in which to save the key (/home/ubiagio/.ssh/id_rsa): biagiopas_sshrsakey
two keys generated
/home/ubiagio/.ssh/
biagiopas_ssh_key
biagiopas_ssh_key.pub
////////////////////////////////////////////
configuration
~/.homestead/Homestead.yaml
ip: "192.168.10.10"
memory: 2048
cpus: 1
provider: virtualbox
#authorize: ~/.ssh/id_rsa.pub
authorize: ~/.ssh/biagiopas_ssh_key.pub
keys:
# - ~/.ssh/id_rsa
- ~/.ssh/biagiopas_sshrsakey
folders:
- map: ~/Code
to: /home/vagrant/Code
sites:
- map: laraveltestblog01.app
to: /var/www/html/laravel/testblog01/public
////////////////////////////////////////////
if the cause is not due to the keys, then may be another problem encountered before
Launching The Vagrant Box
$ cd /home/ubiagio/Homestead/
$ vagrant up
This Vagrant environment has specified that it requires the Vagrant
version to satisfy the following version requirements:
>= 1.8.4
You are running Vagrant 1.8.1, which does not satisfy
these requirements. Please change your Vagrant version or update
the Vagrantfile to allow this Vagrant version. However, be warned
that if the Vagrantfile has specified another version, it probably has
good reason to do so, and changing that may cause the environment to
not function properly.
I tried to upgrade with
$ Sudo apt upgrade
but without success
so I manually changed the Vagrantfile
$ gedit /home/ubiagio/Homestead/Vagrantfile
#Vagrant.require_version '>= 1.8.4'
Vagrant.require_version '>= 1.8.1'
thanks from now for the help