virtualbox.org

Ubuntu 13.04 Guest, Windows 8 Host, Xubuntu 13.04 Guest

I use Fixed Size Storage. After cloning and moving a .VDI to a new machine, so that I could increase the size of the Virtual Hard Drive, I ran into issue where the VBoxGuestAdditions.iso would not mount properly, no matter what I tried. I searched through these forums and other various sites for a solution. Below is what fixed it for me, I hope this will save others some time.
After doing this, I no longer got the lock error and I was able to mount and reinstall the Guest Additions normally.

Tags: VERR_PDM_MEDIA_LOCKED, Unable to mount Guest Additions, Force Unmount, VBoxGuestAdditions.iso failed to mount

Other ideas? I have the same issue.

This new problem started after I previously upgraded guest-additions, but still cannot get bi-directional clipboard to work with a linux-guest and linux-host (though it works fine with a windows-guest on the same linux-host). Now I cannot even mount the Guest Additions iso.

The media locked means that something else is in the virtual CD/DVD drive and you need to eject it. Also you should not download the guest additions from the distro repository. If your host is windows then you already have the new guest additions and simply need to use the device tab to insert the guest additions and install.

Although I tried , it still didn't work for me.

Then I tried click "Devices" -> "Optical Drivers" -> VBoxGuestAdditions.iso", it prompts to ask me "confirm to force eject the optical driver?" and then I clicked "yes".
After that, I tried "Devices" -> "Insert Guest Additons CD Image.." and follows the instructions to reinstall it. Everything is working.

Hope this would help someone else who encounters the same issue as I did.