virtualbox.org

I am running virtualbox on a Windows 10.
Within virtualbox I am running ubuntu 16.04.

I want to install virtualbox guest additions.
This doesn't get mounted automatically for me as other suggest

If I go to the devices tab - but instead of seeing "install guest additions"
I see "Insert Guest Additions CD Image . . ."
If I select this I get the error window with the text below:
"
Unable to insert the virtual optical disk C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso into the machine Ubuntu.



Could not mount the media/drive 'C:\Program Files\Oracle\VirtualBox/VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).

Result Code: E_FAIL (0x80004005)
Component: ConsoleWrap
Interface: IConsole {872da645-4a9b-1727-bee2-5585105b9eed}
Callee: IMachine {b2547866-a0a1-4391-8b86-6952d82efaa0}
"

So how do I get the guest additions iso visible?
Thank you kindly

Seriously? A 7 year old thread? Please open a new one or find a more recent one. Locking this.

And please search before posting. It's only been answered 1000 times so far...