providers/virtualbox: error if can't read VM name [GH-4047]

CHANGELOG.md

@@ -43,6 +43,7 @@ BUG FIXES:
   - hosts/windows: RDP command works without crash. [GH-3962]
   - providers/docker: Port on its own will choose random host port. [GH-3991]
   - providers/virtualbox: Increase network device limit to 36. [GH-4206]
+  - providers/virtualbox: Error if can't detect VM name. [GH-4047]
   - provisioners/chef: Chef client cleanup should work. [GH-4099]
   - provisioners/puppet: Manifest file can be a directory. [GH-4169]
   - provisioners/puppet: Properly escape facter variables for PowerShell

plugins/providers/virtualbox/driver/version_4_3.rb

@@ -171,6 +171,9 @@ module VagrantPlugins
           @logger.debug("Doing dry-run import to determine parallel-safe name...")
           output = execute("import", "-n", ovf)
           result = /Suggested VM name "(.+?)"/.match(output)
+          if !result
+            raise Vagrant::Errors::VirtualBoxNoName, output: output
+          end
           suggested_name = result[1].to_s
 
           # Append millisecond plus a random to the path in case we're
@@ -199,7 +202,7 @@ module VagrantPlugins
               # specified_name were "abc123", then "\\abc123\\".reverse would be "\\321cba\\", and the \3 would be treated as a back reference by the sub
               disk_params << path.reverse.sub("\\#{suggested_name}\\".reverse) { "\\#{specified_name}\\".reverse }.reverse # Replace only last occurrence
             else
-              disk_params << path.reverse.sub("/#{suggested_name}/".reverse, "/#{specified_name}/".reverse).reverse # Replace only last occurrence                
+              disk_params << path.reverse.sub("/#{suggested_name}/".reverse, "/#{specified_name}/".reverse).reverse # Replace only last occurrence
             end
           end
 

templates/locales/en.yml

@@ -1166,6 +1166,16 @@ en:
         VirtualBox is complaining that the installation is incomplete. Please
         run `VBoxManage --version` to see the error message which should contain
         instructions on how to fix this error.
+      virtualbox_no_name: |-
+        Vagrant was unable to determine the recommended name for your
+        VirtualBox VM. This is usually an issue with VirtualBox. The output
+        from VirtualBox is shown below, which may contain an error to fix.
+        The best way to fix this issue is usually to uninstall VirtualBox,
+        restart your computer, then reinstall VirtualBox.
+
+        VirtualBox output:
+
+        %{output}
       virtualbox_no_room_for_high_level_network: |-
         There is no available slots on the VirtualBox VM for the configured
         high-level network interfaces. "private_network" and "public_network"