Last week my wife got prompted by Ubuntu's automatic software update to install a security update that required signing up to some paid Ubuntu subscription.

I'm not sure this is really what it meant (I didn't see the prompt myself), but it was what Ubuntu made her believe.

After updating without this "option", all her VirtualBox VMs stopped working (I don't mean to imply that these two issues are linked).

Ubuntu has a Pro subscription for businesses, which is free for up to five (I think) installs for consumers.

Ubuntu Pro allows for things like patching the kernel while the kernel is running. If you're using VirtualBox, which uses kernel drivers on the host for acceleration, and you do a normal update, you need to reboot to make those drivers work again. You shouldn't need to, but something in Oracle's DKMS driver building process removes the existing drivers for some reason.

If the kernel is replaced while running, the new kernel modules should be loadable immediately and there will only be a brief moment during which VirtualBox wouldn't work.

Ubuntu Pro also provides updates to software packages that weren't maintained before the introduction to Ubuntu Pro (the Universe packages) so it's probably not a bad idea to enable it.

If you don't log in, you'll get the same experience Ubuntu always had before Pro was introduced, which includes the possibility of VirtualBox being broken until you reboot. This isn't Canonical sabotaging your wife's computer, it's just how some updates go down on Ubuntu.

A reboot did not fix the VMs for her. A Google search revealed that she had to install some additional dev package.

I didn't think that Canonical was sabotaging her computer. What I do think is that Canonical is using security updates as an upselling opportunity.

In my opinion this is a bad idea, especially if the language used is vague enough to mislead people.

Thanks. Pretty happy with OSX, and also happy to be spending less time in front of a computer :)