Running VirtualBox latest (5.2.18) without incident until I updated to Ubuntu LTS-18. (Host is OS/X.) Now, shared folders marked "auto-mount" do not mount. (I reinstalled "Guest Additions" from the extension-pack at "virtualbox.org" and restarted, just in case. but no effect.)

I do see the /media/sf_sharename folder for all of the specified shares, but there's nothing in them: they're not mounted!

I can use sudo mount explicitly, and when I do so the content of the shared folder now appears. But, when I specify "auto mount" in the VirtualBox shared-folders setting, I should not have to do this.

Notice that I didn't change anything at all about VirtualBox: I only upgraded Ubuntu. It worked flawlessly until I did this.

(Yes, the user is a member of the appropriate Linux group. It does have permission.)

It's also interesting that /dev/cdrom is also not being mounted ...

2 Answers 2


Here's the summary of the final solution to this problem, based on my original answer below:

Referring to: Virtualbox - folder does not automatically mount, Windows 7 host Ubuntu 17.10 guest

I found that, contrary to the above page, virtualbox-guest-utils.service did not attempt to mount the shares. The vboxadd-service.service does. But you don't have that if you simply install the drivers extension-pack from virtualbox.org. You need to install the extensions from the supplied CD-ROM, which on OS/X is part of the application package.

Then, the Conflicts= instruction was exactly correct:

sudo systemctl edit --full vboxadd-service

... then remove systemd-timesync.service from the Conflicts= list. (Go ahead and do this after you've installed from the CDRom and before you reboot.)

Upon restart, your shares will be there.

Additional supporting information will be found in my original answer, below.


I am revising my answer to be a much better one.

The overall situation I'm experiencing is best described here:


(Although it didn't receive "an answer," it does link to other pages that do, and I've cited some of those pages here.)

The problem appears to be in the vboxadd-serviceand/or the vboxadd-guest-utils-service as discussed in this "askubuntu" page:

Virtualbox - folder does not automatically mount, Windows 7 host Ubuntu 17.10 guest

... which refers to this Ubuntu bug report:


At this writing, I'm trying to ferret out exactly why the service is failing at startup in my case, but I do observe that the service is not running, and that if on my system I execute the following command, the shares appear:

sudo systemctl restart vboxadd-service.service

Unlike the cited post, however, my status for the service shows several services, some "exited":

● vboxadd.service
   Loaded: loaded (/opt/VBoxGuestAdditions-5.2.18/init/vboxadd; enabled; vendor preset: enabled)
   Active: active (exited) since Thu 2018-08-23 12:06:20 EDT; 5min ago
  Process: 905 ExecStart=/opt/VBoxGuestAdditions-5.2.18/init/vboxadd start (code=exited, status=0/SUCCESS)
 Main PID: 905 (code=exited, status=0/SUCCESS)

Aug 23 12:06:00 MyVM systemd[1]: Starting vboxadd.service...
Aug 23 12:06:03 myVM vboxadd[905]: VirtualBox Guest Additions: Starting.
Aug 23 12:06:20 MyVM systemd[1]: Started vboxadd.service.

● vboxadd-service.service
   Loaded: loaded (/opt/VBoxGuestAdditions-5.2.18/init/vboxadd-service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2018-08-23 12:11:20 EDT; 3s ago
  Process: 2696 ExecStart=/opt/VBoxGuestAdditions-5.2.18/init/vboxadd-service start (code=exited, status=0/SUCCESS)
    Tasks: 8 (limit: 4665)
   CGroup: /system.slice/vboxadd-service.service
           └─2737 /usr/sbin/VBoxService --pidfile /var/run/vboxadd-service.sh

Aug 23 12:11:19 MyVM systemd[1]: Starting vboxadd-service.service...
Aug 23 12:11:20 MyVM vboxadd-service[2696]: vboxadd-service.sh: Starting VirtualBox Guest Addition service.
Aug 23 12:11:20 MyVM vboxadd-service.sh[2717]: Starting VirtualBox Guest Addition service.
Aug 23 12:11:20 MyVM vboxadd-service.sh[2736]: VirtualBox Guest Addition service started.
Aug 23 12:11:20 MyVM systemd[1]: Started vboxadd-service.service.

● virtualbox.service - LSB: VirtualBox Linux kernel module
   Loaded: loaded (/etc/init.d/virtualbox; generated)
   Active: active (exited) since Thu 2018-08-23 12:06:08 EDT; 5min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 1356 ExecStart=/etc/init.d/virtualbox start (code=exited, status=0/SUCCESS)

Aug 23 12:06:06 MyVM systemd[1]: Starting LSB: VirtualBox Linux kernel module...
Aug 23 12:06:08 MyVM systemd[1]: Started LSB: VirtualBox Linux kernel module.

Undoubtedly, this "confusion" has considerable bearing on my problem . . .

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