virtualbox.org

I updated VB to the latest version on Ubuntu 18, and I am getting error popups for more than one machine. The one is saying that it "Failed to open a session for the virtual machine", Result Code: NS_ERROR_FAILURE, Component: MachineWrap.

Please provide a VM log file. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.

VirtualBox VM 5.2.18_Ubuntu r123745 linux.amd64 (Oct 10 2018 13:27:01) release log

As I suspected would be the case, that is not the latest version (v6.0.0) of VirtualBox, it isn't even the latest version in the 5.2.x branch (that would be 5.2.22).

To complicate things further, technically your software isn't even VirtualBox. What you have there is the Ubuntu fork of VirtualBox. If you have any issues with the Ubuntu fork of any software then you need to take it to the Ubuntu forums. If you want support on the VirtualBox forums then you need to install official VirtualBox from the downloads site here.

Incidentally, the error message appears to me to suggest that you previously installed official VirtualBox, but then you tried to update it from the Ubuntu repository: which serves up the fork and trashes VirtualBox.

mpack wrote: install official VirtualBox from the downloads site here.

Incidentally, the error message appears to me to suggest that you previously installed official VirtualBox, but then you tried to update it from the Ubuntu repository: which serves up the fork and trashes VirtualBox.

There was no link provided.
I would prefer the updated version. How do I go about fixing this?

Although mpack already told you, I'll repeat with the link, not to hard to find actually...

Completely remove/uninstall/delete/purge their version. Then install the official version from the Linux Downloads section of VirtualBox (https://www.virtualbox.org/wiki/Linux_Downloads).

I did a sudo apt purge virtualbox-*, and 6 still fails to work.

Search your guest's filesystem for anything that starts with virtualb*, vbox*, vm* (case insensitive) and get rid of everything. That should for example find the following ISO, which you should not be having as a stand-alone download:

00:00:00.829168 File system of '/home/user/.config/VirtualBox/VBoxGuestAdditions_5.2.18.iso' (DVD) is ext4

Also uninstall the custom and non-matching VNC ExtPack:

00:00:00.797503 VNC (Version: 5.2.18 r123745; VRDE Module: VBoxVNC)

Since you're on Ubuntu, I suggest that you install 'Synaptic', I find it much easier/user friendly to work with compared to 'dpkg' or 'apt'.