I have three primary partitions. One ext4 format for Ubuntu, one ntfs format for Windows (C:) and one ntfs format for sharing files between Ubuntu and Windows (F:). I installed VirtualBox on both Ubuntu and Windows. I went to VirtualBox Settings and set the Default Machine Folder to F:\VirtualBox VMs on both operating systems.
I created a dynamically allocated VDI (VirtualBox Disk Image) in F:\VirtualBox VMs\my_VM_name and put virtual optical disk file into F:\my_os_name.iso and ran it on Virtualbox in Windows. After installation I also installed VirtualBox guest additions.
I went to Ubuntu, mounted the (F:) partition and added my_VM_name.vbox in VirtualBox. But when I ran it, I get the following error:
The virtual machine execution may run into an error condition as described below. We suggest that you take an appropriate action to avert the error.
The image file
'/media/Ubuntu_user_name/A_Hexadecimal_number/VirtualBox VMs/my_VM_name/C:/Program Files (x86)/Oracle/VirtualBox/VBoxGuestAdditions.iso' is inaccessible and is being ignored. Please select a different image file for the virtual DVD drive..
I closed VirtualBox and ran it again. But it introduce a new error
One or more virtual hard disks, CD/DVD or floppy disk image files are not currently accessible. As a result, you will not be able to operate virtual machines that use these files until they become accessible later.
Press Check to open the Virtual Media Manager window and see which files are inaccessible, or press Ignore to ignore this message.
I pressed the Check and the Virtual Media Manager window shows The following error in the Optical disk tab:
my_os_name.iso*
*Location: /media/Ubuntu_user_name/A_Hexadecimal_number/VirtualBox VMs/my_VM_name/F:/my_os_name.iso
How can I config VirtualBox to work without any errors in both Systems?
Virtualbox stores path information in the .vbox file, it includes the path to the mounted virtual cds, the hard disk path, shared folders paths, etc... The path changes when you change OS (from F:/something to /media/user/hexadecimal_number/something) and the information on the .vbox file becomes invalid.
AFAIK you can't just share the same VMs seamless between both OSes. But you can create a new, identical Virtual Machine in Linux that uses the same Virtual Hard Disk and Virtual Hardware than the Windows one (but a different vbox file). This should be close enough to what you want to achieve.