Comment 67 for bug 1926937

Hi Eduardo, as pointed out earlier by Simon, the virtualbox-guest-additions-iso and virtualbox-ext-pack packages are separate and are not installed automatically. Did you have these packages installed before?

From the terminal, use "sudo apt list virtualbox*" to check their status on your system.

For my Focal system, after upgrading virtualbox to 6.1.26 from the repo, I checked from the VirtualBox GUI via Tools -> Preferences -> Extensions and found that the "VNC" extension was now on version 6.1.26 but that the "Oracle VM VirtualBox Extension Pack" was still on version 6.1.22. Rather than downloading the latest extension pack from the oracle website and updating it in the GUI directly as I did before, this time I (first closed the GUI) installed the package for it via terminal "sudo apt install virtualbox-ext-pack" and when I went back into the GUI to check it was updated there.

Same with installing the virtualbox-guest-additions-iso package, I did not need to download the latest guest additions inside of the Guest OS, which I was prompted to do when the latest ISO could not be found before.

So long as these related packages are updated in line with the main virtualbox packages in future, then I think it will be automatic next time, but you do need to make sure they are installed on your system first.