# Unable to mount VirtualBox Guest Additions as a guest (Win7 host)

I keep getting this error dialog with an Unable to mount error E_FAIL ( 0x80004005 ) when I try to mount Guest Additions:

I tried the Force Unmount, but that just closes the dialog with no action taken. If I then reattempt to mount Guest Additions, I just get this same dialog box again. Any help would be greatly appreciated!

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Finally, I figured it out. Here is how you get arount this. First, load Disk Utility and manually eject the disk in the CDROM, by clicking on the Eject button, after selecting the CDROM device. Then try to remount Guest Additions using the key combination Host + D and voila, Guest Additions should mount successfully.

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Just a quick note, I tried this today and was unable to eject the media. I had to go down a little further on the page and select "Unmount Volume", and then I was able to Eject. –  Chris Sobolewski Oct 14 '13 at 23:37
I believe disk utility is a GUI application, yes? How can I achieve what you accomplished here through the command line? –  jeff fabiny Dec 17 '14 at 15:42

I could not get the autorun to work, installed manually by doing:

cd /media/VBOXADDITIONS_4.2.4_81684/

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thanks! this worked nicely and all from cmdline. Only path to additions may vary, for me it was - 'cd /media/kerim/VBOXADDITIONS_4.2.10_84104/' –  kerim Apr 3 '13 at 10:12
I had to perform a mixture of this step and Michael Goldshteyn's steps: 1) sudo palimpsest for complete access to device and eject. 2) remount disk 3) sudo sh /media/VBOXADDITIONS_4.3.6_91406/VBoxLinuxAdditions.run did the trick. –  Screenack Dec 21 '13 at 14:42

1. Unmount Volume
2. Eject
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Unmounting the volume on devices -> CD -> Remove disk from virutal drive

This will show the "Remove disk from Virtual drive" option as disabled on the same page once you clicked.

Then Press Host (Keyboard:Right Ctrl) + D i.e Host+D

This started working installing automatically on my Ubuntu screen.

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I ran into this error under this scenario.

1. Turned on Fedora 18
2. Opened Terminal, Logged in as root
3. Attempted to install Guest Additions. It failed with a package missing error
4. Installed the package and rebooted the system
5. Logged in as guest user and attempted to run Guest Addition, as I was thinking logging in root is not necessary

No matter how many tries I did, I kept on running into VERR_PEM_MEDIA_LOCKED error.

Trying to install by logging into root made this error go away.

So, it seems the OS somehow remembers the user you tried to run the Guest Additions first time, and in successive runs, if you are not logged as that user, it complains.

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Here is what I followed and it worked. Nothing else. Mine is Ubuntu 14.04 Trusty...

1) Once in Ubuntu, Go to the files folder.

2) On the left side, you will see some options among which there will be "My Computer" and above it "The virtual drive (Named as your ISO file)"

3) Right click on it and select eject.

4) Go back to the "VIRTUALBOX" and go to devices option and select Install Guest Addition CD Image.

5) Hopefully, you wont get the same error.

7) Let the terminal run and once asked, press enter.

8) Reboot your Virtualbox and this time you will notice the full resolution version.

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# Alternative Workaround for Such an issue

"If all else fails"

I just climb through the network anty copy it to the drive. Mount it as loop.

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I came across this today and it seems it could not be fixed via GUI operations. So I did it via command line. It worked like a charm!

1. Devices -> Install Guest Additions...(it's like insert a cd to cdrom)
2. Open a terminal to login the guest machine
3. Type below

sudo mkdir --p /media/cdrom
sudo mount -t auto /dev/cdrom media/cdrom/
cd /media/cdrom/