Comment 4 for bug 1851186

Still doesn't work for me :-(

I have the same plugin version as Yasuo Honda ^ so I'm thinking could it be related to VirtualBox and guest additions versions ?

Here's the output of my attempt:

% /tmp/vagrant_ubuntu_bug$ VBoxManage --version
5.2.34_Ubuntur133883

% /tmp/vagrant_ubuntu_bug$ vagrant version
Installed Version: 2.2.2

% /tmp/vagrant_ubuntu_bug$ vagrant plugin list
vagrant-disksize (0.1.3, global)
vagrant-hosts (2.9.0, global)
vagrant-vbguest (0.23.0, global)

% /tmp/vagrant_ubuntu_bug$ vagrant box list
ubuntu/focal64 (virtualbox, 20200428.0.0)

% /tmp/vagrant_ubuntu_bug$ cat Vagrantfile
Vagrant.configure("2") do |config|

  config.vm.box = "ubuntu/focal64"

  config.vm.provider :virtualbox do |vb|
    vb.memory = 2048
    vb.cpus = 4
  end

end

% /tmp/vagrant_ubuntu_bug$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'ubuntu/focal64'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'ubuntu/focal64' is up to date...
==> default: Setting the name of the VM: vagrant_ubuntu_bug_default_1588151986857_63626
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
    default: Adapter 1: nat
==> default: Forwarding ports...
    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: Warning: Connection reset. Retrying...
    default: Warning: Remote connection disconnect. Retrying...
    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] No Virtualbox Guest Additions installation found.
rmmod: ERROR: Module vboxsf is not currently loaded
rmmod: ERROR: Module vboxguest is not currently loaded
Reading package lists...
Building dependency tree...
Reading state information...
Package 'virtualbox-guest-x11' is not installed, so not removed
The following packages will be REMOVED:
  virtualbox-guest-utils*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 5832 kB disk space will be freed.
(Reading database ... 62770 files and directories currently installed.)
Removing virtualbox-guest-utils (6.1.6-dfsg-1) ...
Processing triggers for man-db (2.9.1-1) ...
(Reading database ... 62757 files and directories currently installed.)
Purging configuration files for virtualbox-guest-utils (6.1.6-dfsg-1) ...
Processing triggers for systemd (245.4-4ubuntu3) ...
Reading package lists...
Building dependency tree...
Reading state information...
linux-headers-5.4.0-28-generic is already the newest version (5.4.0-28.32).
linux-headers-5.4.0-28-generic set to manually installed.
The following additional packages will be installed:
  binutils binutils-common binutils-x86-64-linux-gnu build-essential cpp cpp-9
  dpkg-dev fakeroot g++ g++-9 gcc gcc-9 gcc-9-base libalgorithm-diff-perl
  libalgorithm-diff-xs-perl libalgorithm-merge-perl libasan5 libatomic1
  libbinutils libc-dev-bin libc6-dev libcc1-0 libcrypt-dev libctf-nobfd0
  libctf0 libdpkg-perl libfakeroot libfile-fcntllock-perl libgcc-9-dev
  libgomp1 libisl22 libitm1 liblsan0 libmpc3 libquadmath0 libstdc++-9-dev
  libtsan0 libubsan1 linux-libc-dev make manpages-dev
Suggested packages:
  binutils-doc cpp-doc gcc-9-locales menu debian-keyring g++-multilib
  g++-9-multilib gcc-9-doc gcc-multilib autoconf automake libtool flex bison
  gdb gcc-doc gcc-9-multilib glibc-doc bzr libstdc++-9-doc make-doc
The following NEW packages will be installed:
  binutils binutils-common binutils-x86-64-linux-gnu build-essential cpp cpp-9
  dkms dpkg-dev fakeroot g++ g++-9 gcc gcc-9 gcc-9-base libalgorithm-diff-perl
  libalgorithm-diff-xs-perl libalgorithm-merge-perl libasan5 libatomic1
  libbinutils libc-dev-bin libc6-dev libcc1-0 libcrypt-dev libctf-nobfd0
  libctf0 libdpkg-perl libfakeroot libfile-fcntllock-perl libgcc-9-dev
  libgomp1 libisl22 libitm1 liblsan0 libmpc3 libquadmath0 libstdc++-9-dev
  libtsan0 libubsan1 linux-libc-dev make manpages-dev
0 upgraded, 42 newly installed, 0 to remove and 0 not upgraded.
Need to get 40.0 MB of archives.
After this operation, 175 MB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu focal/main amd64 gcc-9-base amd64 9.3.0-10ubuntu2 [19.3 kB]
[...]
Get:42 http://archive.ubuntu.com/ubuntu focal/main amd64 manpages-dev all 5.05-1 [2266 kB]
dpkg-preconfigure: unable to re-open stdin: No such file or directory
Fetched 40.0 MB in 3s (12.1 MB/s)
Selecting previously unselected package gcc-9-base:amd64.
(Reading database ... 62756 files and directories currently installed.)
Preparing to unpack .../00-gcc-9-base_9.3.0-10ubuntu2_amd64.deb ...
Unpacking gcc-9-base:amd64 (9.3.0-10ubuntu2) ...
Selecting previously unselected package libisl22:amd64.
Preparing to unpack .../01-libisl22_0.22.1-1_amd64.deb ...
[...]
Selecting previously unselected package manpages-dev.
Preparing to unpack .../41-manpages-dev_5.05-1_all.deb ...
Unpacking manpages-dev (5.05-1) ...
Setting up manpages-dev (5.05-1) ...
[...]
Setting up g++ (4:9.3.0-1ubuntu2) ...
update-alternatives: using /usr/bin/g++ to provide /usr/bin/c++ (c++) in auto mode
Setting up build-essential (12.8ubuntu1) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for libc-bin (2.31-0ubuntu9) ...
Copy iso file /usr/share/virtualbox/VBoxGuestAdditions.iso into the box /tmp/VBoxGuestAdditions.iso
Mounting Virtualbox Guest Additions ISO to: /mnt
mount: /mnt: WARNING: device write-protected, mounted read-only.
Installing Virtualbox Guest Additions 5.2.34 - guest version is unknown
Verifying archive integrity... All good.
Uncompressing VirtualBox 5.2.34 Guest Additions for Linux........
VirtualBox Guest Additions installer
Copying additional installer modules ...
Installing additional modules ...
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup <version>
VirtualBox Guest Additions: Building the modules for kernel 5.4.0-28-generic.

VirtualBox Guest Additions: Look at /var/log/vboxadd-setup.log to find out what
went wrong
VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the modules for kernel 5.4.0-28-generic.

VirtualBox Guest Additions: Look at /var/log/vboxadd-setup.log to find out what
went wrong
An error occurred during installation of VirtualBox Guest Additions 5.2.34. Some functionality may not work as intended.
In most cases it is OK that the "Window System drivers" installation failed.
Job for vboxadd.service failed because the control process exited with error code.
See "systemctl status vboxadd.service" and "journalctl -xe" for details.
Unmounting Virtualbox Guest Additions ISO from: /mnt
==> default: Checking for guest additions in VM...
    default: No guest additions were detected on the base box for this VM! Guest
    default: additions are required for forwarded ports, shared folders, host only
    default: networking, and more. If SSH fails on this machine, please install
    default: the guest additions and repackage the box to continue.
    default:
    default: This is not an error message; everything may continue to work properly,
    default: in which case you may ignore this message.
==> default: Mounting shared folders...
    default: /vagrant => /tmp/vagrant_ubuntu_bug
Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:

mount -t vboxsf -o uid=1000,gid=1000 vagrant /vagrant

The error output from the command was:

: No such device