VirtualBox does not support shrinking disk sizes. Cannot shr

Error message

VirtualBox does not support shrinking disk sizes. Cannot shrink '%{name}' disks size.

What it means

Error "VirtualBox does not support shrinking disk sizes. Cannot shrink '%{name}' disks size." thrown in hashicorp/vagrant.

Source

Thrown at plugins/providers/hyperv/cap/configure_disks.rb:164

        end

        # Check to see if current disk is configured based on defined_disks
        #
        # @param [Kernel_V2::VagrantConfigDisk] disk_config
        # @param [Hash] defined_disk
        # @return [Boolean]
        def self.compare_disk_size(machine, disk_config, defined_disk)
          # Hyper-V returns disk size in bytes
          requested_disk_size = disk_config.size
          disk_actual = machine.provider.driver.get_disk(defined_disk["Path"])
          defined_disk_size = disk_actual["Size"]

          if defined_disk_size > requested_disk_size
            if File.extname(disk_actual["Path"]) == ".vhdx"
              # VHDX formats can be shrunk
              return true
            else
              machine.ui.warn(I18n.t("vagrant.cap.configure_disks.shrink_size_not_supported", name: disk_config.name))
              return false
            end
          elsif defined_disk_size < requested_disk_size
            return true
          else
            return false
          end
        end

        # Creates and attaches a disk to a machine
        #
        # @param [Vagrant::Machine] machine
        # @param [Kernel_V2::VagrantConfigDisk] disk_config
        def self.create_disk(machine, disk_config)
          machine.ui.detail(I18n.t("vagrant.cap.configure_disks.create_disk", name: disk_config.name))
          disk_provider_config = {}

          if disk_config.provider_config && disk_config.provider_config.key?(:hyperv)

View on GitHub (pinned to 35f3160f4a)

When it happens

Trigger: Thrown at plugins/providers/hyperv/cap/configure_disks.rb:164 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hashicorp/vagrant@35f3160f4a (2026-08-21). Data as JSON: /api/errors/302f9942d19176ea. Report an issue: GitHub.