Error if no available network adapters are found

lib/vagrant/action/vm/network.rb

@@ -90,6 +90,11 @@ module Vagrant
           adapters.each do |adapter|
             # Ignore the adapters that already have been assigned
             if !adapter[:adapter]
+              # If we have no available adapters, then that is an exceptional
+              # event.
+              raise Errors::NetworkNoAdapters if available.empty?
+
+              # Otherwise, assign as the adapter the next available item
               adapter[:adapter] = available.shift
             end
           end

lib/vagrant/errors.rb

@@ -208,6 +208,11 @@ module Vagrant
       error_key(:collides, "vagrant.actions.vm.host_only_network")
     end
 
+    class NetworkNoAdapters < VagrantError
+      status_code(64)
+      error_key(:no_adapters, "vagrant.actions.vm.network")
+    end
+
     class NetworkNotFound < VagrantError
       status_code(30)
       error_key(:not_found, "vagrant.actions.vm.host_only_network")

templates/locales/en.yml

@@ -395,10 +395,15 @@ en:
             MAC address is typically up to the box and box maintiner. Please contact
             the relevant person to solve this issue.
         network:
-          preparing: |-
-            Preparing network interfaces based on configuration...
           configuring: |-
             Configuring and enabling network interfaces...
+          no_adapters: |-
+            No available adapters on the virtual machine were found to accomodate
+            for all configured networks. VirtualBox virtual machines have 8
+            network interfaces available usually, so please lower the number of
+            networks to below 8.
+          preparing: |-
+            Preparing network interfaces based on configuration...
         host_only_network:
           collides: |-
             The specified host network collides with a non-hostonly network!