Ubuntu 18.04 lts freezes while in boot, in wndows Virtual box. Solution?

i've had the same issue:

• 3D acceleration = off
• 10 GB Ram

My solution was:

• 1 processor => 4 processors
• enable PAE/NX

Several of my old VMs seem to hang on bootup. If in Grub I select "recovery mode", the last messages displayed on the screen are:

smp: Bringing up secondary CPUs...
x86: Booting SMP configuration:

Then it hangs.

In my case, I can confirm that for all my VMs experiencing this problem, changing the Virtualbox setting "System -> Acceleration -> Paravirtualization Interface" from "Legacy" to "Default" enabled these old VMs to work again. Switching it back to "Legacy" immediately makes it hang on boot, so I know for certain this is the key to the issue in my case.

Did you allocate enough RAM to the virtual machine? Give it 2GB or more RAM. I discovered when I ran Ubuntu 18.04 live cd on virtual box, it froze at some point, but on allocation of more RAM, I got it working perfectly