virtualbox.org

I have a brand-new Win 10 Pro machine (build 18363.836). I had a quick play with Hyper-V, but decided that I prefer VBox (things like shared folders don't seem to exist in Hyper-V, and machine management has an absolute nightmare of a control panel). So I've been trying to install various 64-bit Ubuntu flavors (Ubuntu, Xubuntu, 18.04, 20.04) inside VBox 6.1.8, but I can't get any of them to work -- no matter which one I try, it fails with any one of a number of different symptoms:

1) Sometimes it crashes during install: "The installer encountered an error copying files to the hard disk. [Errno 5] Input/output error. This is often due to a faulty CD/DVD disk/drive or hard disk. It may help to clean the CD/DVD." (!)

2) If I try again, maybe it doesn't fail like this but gets to the point where I have a functioning desktop. I take a snapshot. Then if I install the Guest Additions and reboot, it loses all my desktop settings and gives me a login screen (even though I asked for auto-login) but refuses to accept my password.

3) If I restore the snapshot to the point before I install the GAs, it usually starts up but sometimes the system is completely unresponsive, ignoring mouse clicks and keypresses (although it will move the mouse).

4) If I'm lucky and this doesn't happen, I open the default web browser (Firefox) and set the home page etc., or try to install Adblock Plus, and then it locks up in the same way as above.

5) Reverting to earlier snapshots (I'm now taking one after every change I make) doesn't help -- the earlier snapshots sometimes work, they sometimes start off locked up completely, they sometimes report mysterious "hardware" errors.

6) Sometimes it also locks up in the middle of the installation process, at the point where I have to choose a keyboard, time zone or username.

I've tried disabling Hyper-V on the Windows host, I've tried disabling paravirtualisation -- nothing I've tried helps.

Does anyone have any idea what might be going on here?

Hyper-V is a somewhat harder, but not impossible, beast to vanquish. Go through every step in I have a 64bit host, but can't install 64bit guests.

For further info, see https://www.tenforums.com/tutorials/139 ... puter.html

Recommendation, don't use snapshots, unless you experiment with them on throw-away guests and data first until you are really proficient at using them on the throw-away guests and know exactly what snapshots do.

Snapshots make a guest more delicate and do not work as backups. They are similar to Windows' System Restore points: they are point-in-past-time markers, not extractable, useless without the base system in place, but easier to corrupt because the files are accessible on the host drive. They do not store "files", like a backup folder would. Virtualbox snapshots store changed disk sectors, which may or may not contain the entire file. They should only be used on guests you're experimenting with and with data you wouldn't mind losing. (The forums are replete with users destroying their important data because they did something wrong with a snapshot.)

Thanks. I hadn't realised that Hyper-V was the Japanese Knotweed of the Windows world.

As for snapshots: don't worry, I've been using VBox for at least the last 15 years -- probably longer, come to think of it. I was taking snapshots because of all the crashes; I wanted to be able to roll back to known-good states and start again from there, rather than tear it all down and reinstall from scratch. Later I can merge them into a unified image.

I've disabled all the dozens of things on the list you pointed me at, did the bcdedit spell (which is also not as easy as it sounds, since you first have to track down bcdedit.exe to its lair) -- on reboot, bcdedit reports "hypervisorlaunchtype Off" -- but unfortunately it has made no difference at all; Xubuntu 20.04 appeared to install but won't boot at all, and Xubuntu 18.04 went into Guru Meditation mode with a triple fault the first time, and went back to claiming I should clean my installation CD the second time. So I'm still stumped.

BTW: I have also tried 32-bit Ubuntus, and old saved VMs from my archives, and none of them work for more than a minute or two before locking up. I also tried uninstalling VBox 6 and installing 5.2.46 instead -- still no luck.

Lets take a look at a guest log if possible. Start a guest from full power off, not save-state. Run until you see the problem happen, then shut down the guest from within the guest OS if possible. If not possible, close the Virtualbox window for the guest with the Power Off option set.

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

OK, here you go. There are 3 logs here:
1) Xubuntu 18.04-2020-05-19-19-26-05.log, which hung up at the end of the installation process just before the normal "remove CD and press Enter" prompt
2) Xubuntu 18.04-2020-05-19-19-49-35.log, which got as far as me installing initial updates, configuring the desktop, installing GAs and rebooting. I then connected a shared folder and rebooted, and got a login prompt which refused to accept my password.
3) Xubuntu 20.04-2020-05-19-19-03-54.log, which installed, asked me to remove CD and press Enter, and then rebooted. When it restarts, it just says "Decoding failed -- System halted" and stops.

All three logs contain these lines:

{timestamp} HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
{timestamp} NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

You might notice in the guest window's Status Bar the green turtle: The choice of animal is appropriate: Your guest is running, just really slow. Or it might guru-meditate. This is because a service that uses Microsoft Hyper-V is running on your host PC. Normally Hyper-V blocks Virtualbox. But your PC is of the type and OS where Virtualbox can attempt to run the guest using the Hyper-V engine. This arrangement is still being developed and isn't 100% yet.

If VirtualBox is running without Hyper-V enabled, and nothing else is interfering with hardware virtualization (VT-x / AMD-V), then the usual virtualization icon () will be seen in the Status Bar.

To turn Hyper-V off completely, do this:

1. Shut down all programs. You will have to reboot your host.

2. See I have a 64bit host, but can't install 64bit guests. This tutorial has a couple more things to look for in step 2. Be sure these are all turned off.

3. Find the Command Prompt icon, right click it and choose Run As Administrator.

4. Enter this command:

bcdedit /set hypervisorlaunchtype off

5. Enter this command:

shutdown -s -t 2

6. When the computer turns off, unplug it for 20 seconds. Then plug it in again and boot up Windows 10.

If your Virtualbox does not start successfully, zip and post another vbox.log. For further info, see https://www.tenforums.com/tutorials/139 ... puter.html

Excellent, you're a star! Thanks for all your help. I can't do anything about this right now, but I'll try later and let you know what happens. Again, many thanks.

OK, I found one remaining bit of knotweed (aka Hyper-V) that I'd missed in Windows Features, and the turtle has now swum away, leaving me with a nice purple V. The 64-bit machines wouldn't even start ("a virtual macine could not be created for.." or some such) so I deleted them and started a new one. An old 32-bit one that I still need works, and despite the old version of the GAs (v4 I think), it seems to be happy -- I can resize the desktop, cut & paste between host and guest, all that stuff.

The new 64-bit machine installed without any trouble. I went to install the GAs and spotted an interesting difference: on previous installs it always complained that it couldn't build the kernel modules and wanted me to install gcc, make and perl (which I found a bit odd) but this time it built them without complaining. I took a precautionary snapshot and then restarted... and found I had the same issue as before: my desktop settings had been destroyed, and I was faced with a login prompt that refused to accept my password. I'm attaching screenshots of the before-and-after state in case you or anyone else has seen this before... and I'll ask about it in a separate thread, since you've solved the main issue here for me.

THANK YOU!