Ubuntu VM stuck on black screen with a white underscore, no apparent error

[G kp]

(mod edit: split from viewtopic.php?f=6&t=98281)

Since you have plenty of RAM in your host, you should simply provide the maximum of 128 MB VRAM to the guest (even if 18 MB could be enough for a full HD resolution).

Additionally, you declared the Guest OS as Ubuntu (32-bit) with 16 GB of RAM, which seems illogical. Because of this, VirtualBox does not provide an I/O-APIC and other 64-bit capabilities to the guest OS, and if the guest OS is a 64-bit Ubuntu, it may or may not be able to cope with that.

Lastly, most of the time it makes sense to provide 2 vCPUs to a guest OS.

i have the same issue, blackscreen with blinking underscore. Similar scenario( problem started after installing docker, have hyper-v support), i tried to increase the vram to 128, it didnt work same issue, regardless the vm was working fine(albeit slow) before with just 32mb vram.

my host hast 8Gb ram total so i kept it low as i use virtual box very little. This started when i installed docker and the pc crashed with a bluescreen. my ubuntu vm has been acting up since and increasing vram hasn't worked.( i'm not sure what to do with hyper v). But regardless is there any other fix then increasing vram and if we find a fix can i reduce vram and still use it like before?

[scottgus1]

Enabling Hyper-V-based services can have different effects on different computers, as a perusal of the last few years of the forum will show. So it could be possible that one person's solution might not work for another person.

Please Start the VM from full normal shutdown, not save-state. Run until you see the problem happen, then shut down the VM from within the VM's OS if possible. If not possible, close the Virtualbox window for the VM with the Power Off option set.

Right-click the VM in the main Virtualbox window's VM list, choose Show Log. Save the far left tab's log, zip it, and post the zip file, using the forum's Upload Attachment tab.