PowerShell null reference error when importing Hyper-V VM with VMMS not running

[mrshanahan]

Vagrant version

2.2.5

Host operating system

Windows 10 (1709)

Guest operating system

Windows Server 2012 R2

Vagrantfile

Nothing specific:

Vagrant.configure("2") do |config|
  config.vm.box = "<custom-hyperv-box>"
end

Debug output

https://gist.github.com/mrshanahan/58edae984050bcb94dafae8ddd8545d1

Expected behavior

The command fails with a helpful error message, possibly indicating that VMMS is down.

Actual behavior

The import_vm.ps1 script fails with the following error:

You cannot call a method on a null-valued expression.

Steps to reproduce

1. Disable the VMMS service ("Hyper-V Virtual Machine Management"). (PowerShell: Get-Service vmms | Stop-Service)
2. Initialize a new Vagrant directory with a bare-bones Vagrantfile pointing at a Hyper-V box:

Vagrant.configure("2") do |config|
  config.vm.box = "<some-hyperv-box>"
end

3. Run vagrant up (with --provider hyperv as necessary with the box).

Root cause

I've found the root cause and will open a PR ASAP. Just wanted to create an issue to track it.

Vagrant fails to create a VM due to VMMS not running, which is expected behavior. It then attempts to create a more helpful error message for the failed import, and starts by querying WMI for the VMMS service:

vagrant/plugins/providers/hyperv/scripts/utils/VagrantVM/VagrantVM.psm1

Line 357 in 83ed018

$ManagementService = Get-WmiObject -Namespace 'root\virtualization\v2' -Class 'Msvm_VirtualSystemManagementService'

Since this service is not running, the return value is null, and the attempt to import the system definition from the null service fails:

vagrant/plugins/providers/hyperv/scripts/utils/VagrantVM/VagrantVM.psm1

Line 364 in 83ed018

$Result = $ManagementService.ImportSystemDefinition($FullPathFile, $null, $true)

Checking for null after querying the service and throwing a more specific message should do the trick.

[briancain]

Closing this since the pull request was merged.

[mrshanahan]

Thank you!

[ghost]

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