virtualbox.org

A few days ago I successfully created a 64 bit Linux guest machine on my 64 bit Windows 10 host. Today, when I tried to boot the guest again (I've booted it several times successfully before today), it freezes on boot.

After fiddling around, trying to get it to boot, I decide to simply create a new one. When I click new, the only versions available to me are 32 bit.

I've looked around the forums for an answer, and most answers involve VT-x availability. I am not very knowledgeable about Virtual Machines in general, but I am pretty sure VT-x is available given that I have booted the 64 bit guest on multiple occasions prior. The only thing I did from the last time I booted the guest until now is shut down my PC.

Take a look at this: I have a 64bit host, but can't install 64bit guests
If you could run the 64-bit guest before but can't run it now, something new is taking up VT-x on your PC. AV update, hyper-v getting turned on, programming IDE installed, etc.

That post is what I am referring to. I have no AV updates, disabled all that junk a long time ago. HyperV is off. Nothing has changed since I booted the guest the last time.

Having Virtualbox's 64-bit capability suddenly disappear is a sure sign of something else using it first.

Try to start a 64-bit machine, let it error and close. Then post the zipped log for that run (see Minimum info needed to find the log). The log will confirm whether the VT-x is being taken away from your Virtualbox.

If VT-x is being taken, then that's why Virtualbox can no longer run 64-bit guests. Unfortunately Virtualbox has no tool to tell what is using VT-x. VT-x doesn't just disappear off a PC like a program might, it must be turned off in the BIOS or taken by another program before Virtualbox can take it.

I just saw this:

HyperV is off

Does that mean you're not using it, or have you completely disabled and uninstalled it, and cold-shut-down & re-powered-up the PC?

I have disabled HyperV through the "Turn Windows Features On or Off" option from the control panel. I am not sure if that means it is uninstalled, but I did do a cold boot today.

I'm not completely familiar with VirtualBox, but I have attached a log file. If that is not the right one, I'll see if I can figure that out.

Edit: I've replaced it with a zip file of the VBoxHardening.log because I originally attached just the VBox.log

You did find the correct log, good! This line: seems to say VT-x is turned off or at least unavailable to Virtualbox. Double-check that VT-x is actually still on in the BIOS, and double-check that your processor is actually VT-x-capable, and that hyper-v is really unchecked in "Turn Windows Features On or Off". Aside from that, I would not be able to suggest anything else.

Phone emulators, antivirus, integrated development environments, etc., have been reported to interfere with Virtualbox's usage of VT-x. Test-removing these programs or poking around in their properties pages and finding & deactivating their hardware virtualization usage would be necessary to allow Virtualbox to run 64-bit again.

scottgus1 wrote:and double-check that your processor is actually VT-x-capable

I appreciate that you're giving me all the solutions you can think of, but I'd say yes, it is because I could run the machine before

That being said, however, I double checked the BIOS settings and everything was in place, so I cold-booted it again just to see what would happen and suddenly the Intel Virtualization Technology setting was disabled. Enabled and booted to success.

I would be remiss, however, if I just assumed everything will be hunky dory from here on out, because I can't recall doing anything that would prompt this to happen. Thank you for your help, and I'll be back here mewling for more if things go nuts again

Interesting. Maybe a bad BIOS chip? Put a note up somewhere for if it happens again
Glad it's working now!