virtualbox.org

I got the pop up this morning telling me about the new update, which I gladly downloaded and installed.

Everything was working fine before the update. Now I can't start any of my 64bit vmachines. I keep getting the "VT-x is not available" error. When I have my 64bit Windows 8.1 session selected, the "General" section still shows that my OS is Windows 8.1 (64 bit). But if I go into settings for that particular machine, it reverts back to Windows XP (32 bit) and there aren't any 64 bit options in the Version dropdown.

More detail on my error:
VT-x is not available. (VERR_VMX_NO_VMX).
Result Code: E_FAIL (0x80004005)
Component: Console
Interface: IConsole {8ab7c520-2442-4b66-8d74-4ff1e195d2b6}

Hyper V isn't running on my host, and I have plenty of RAM to work with.

Any ideas? Do I need to provide more detail?

Any help would be greatly appreciated!

Post a VM log file (zipped) showing the problem: Minimum information needed for assistance.

I assume you've searched for previous discussion of the issues with Windows 8 hosts and are aware that you need to disable the Hyper-v VM service.

@mpack, I've had vbox for several years so was aware to kill Hyper-V. I'm a little confused as to how Hyper-V was reinstalled (perhaps with a MS update), but my guest sessions were running yesterday and updating to the new version just so happened to be coincidental to Hyper-V coming back on.

Also, "disabling the Hyper-V service" is a tricky phrase. You can disable it in services.msc, but what you really want to do is uninstall Hyper-V as a feature all-together. Once I realized what had happened to my host and made the necessary changes, my guests can all run freely again.

Sorry again for the cross post.

As long as the service isn't running, it shouldn't cause a problem - so it should't have been necessary to uninstall Hyper-v. However that's academic now.

Basically, it's perfectly ok to have other VM platforms installed, they simply musn't be running and using VT-x/AMD-v when VirtualBox wants it.