How to solve Cannot install Guest Addtions: VERR_PDM_MEDIA_LOCKED

Today I’ve updated my VirtualBox to version 4.1.16-78094. When I tried to install the new version of Guest Additions, I got the error message

as you can see in the picture 1 bellow

Picture 1 – error message when trying to install Gest Additions

Notice that clicking in the Force Unmount button has no effect.

The solution is simple: unmount the CD/DVD driver.

After that you will be able install the Guest Additions.

Just as a reference:

My host: Windows 7 64 bits sp1

My Guest: Ubuntu 12.04 32 bits.

Hope it helps.



14 thoughts on “How to solve Cannot install Guest Addtions: VERR_PDM_MEDIA_LOCKED”

      1. Yeah, “sudo umount”, except this is a Windows host computer w/xUbuntu guest, hehe. xD

        (It’s *simple* and it “works”, once you can figure out WTH is going on; but, to get there – you’ll need to go to hell & back :))

    1. It’s a matter of browsing the sub folders in /media and /mnt.

      Another way is to open the terminal and issue the command
      mount|grep ^’/dev’

      You will see something like

      /dev/sda2 on / type ext3 (rw,relatime,errors=remount-ro)

      /dev/sda1 on /media/Windows-XP-x64 type fuseblk (rw,nosuid,nodev,allow_other,blksize=4096)

      /dev/sr0 on /media/cdrom0 type iso9660 (ro,nosuid,nodev,user=ozzman)

      You will look for iso9660 string. In the sample above, the CD / DVD was mounted on /media/cdrom0.

      1. Hi Marcio. Thanks for your reply! I had initially installed XAMPP on Windows, but now would like to move it to the virtual Linux environment. Is it possible to copy the files using “Install Guest Additions” or should I download a fresh XAMPP on the Linux OS?

    1. Hi.

      Assuming that no error message is issued, a probability is that the VBoxGuestAdditions.iso is damaged. It happened once to me. A way to see if it is damaged is to try to open it with 7zip. If 7zip were unable to open VBoxGuestAdditions.iso, so its damaged and I recommend you to download a fresh version of VirtualBox in order to get a new file.

      Otherwise I cannot help because I didn’t have any other problems beside the ones in the post and in this comment.


  1. man this is really pathetic, this fking guest additions is a waste of fking time, it doesnt bloody work, nobody can explain step-by-step how to get it working

    either its because i still have a AMD Athlon XP 2800+ i dont know, bu ti have followed the forums and i dont bloody understand how to make the screen bigger of the OD,. i have spent hours on this and just not managing

  2. Marcio Andrey Oliveira – You don’t give any information on HOW to unmount the CD/DVD drive. As far as my computer knows?…there’s nothing in it’s drive so there’s nothing to be unmounted. Could you be a bit more specific and detailed in your explanations?

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