virtualbox.org

Hi,

I don't know why, but my CentOS8 virtual machine does not start anymore it gets stuck on the black screen with the Centos logo at the bottom.

You can see in attachment the VBox.log

I am very annoyed because I would like to retrieve an nginx configuration file on my machine, but since it does not start anymore

if someone could help me i would be very grateful

thanks in advance

Zorus wrote: I don't know why, but my CentOS8 virtual machine does not start anymore

It's the usual reason: Hyper-v is enabled.

00:00:03.953765 HM: HMR3Init: Attempting fall back to NEM: VT-x is not available
00:00:04.013608 NEM: WHvCapabilityCodeHypervisorPresent is TRUE, so this might work...

See HMR3Init: Attempting fall back to NEM (Hyper-V is active).

I recommend that you also cut the VM CPU allocation to 2 cores. Currently you don't leave any cores at all for the exclusive use of the host. VirtualBox is a host app, it will not appreciate having no CPU. I would also enable 3D acceleration and max out graphics RAM.

And install the host Extension Pack.

Also, why are you running GAs from a test build of VirtualBox? Generally speaking, having GAs from a later version of the software is a big no-no.

Also, I see that the VM is running from drive F. I would hope that isn't a USB flash drive or network drive, otherwise that will badly affect VM performance.

Hello,

The drive F: is not a USB key but a hard drive.
So i put 2core instead of 4/8.

I executed this commands in admin console:

bcdedit /set hypervisorlaunchtype off

and

DISM /Online /Disable-Feature:Microsoft-Hyper-V

and i reboot after....but unfortunately i have the same behavior.

This is my new log

You got Hyper-V turned off, processors reduced, and 3D enabled, that's good.

The VM log does not show problems in the VM hardware.

Test-build Guest Additions is still installed:

00:00:02.978157 VirtualBox VM 6.1.26 r145957 win.amd64 (Jul 28 2021 17:15:09) release log
00:00:16.128204 VMMDev: Guest Additions information report: Version 6.1.27 r146191 '6.1.27'

mpack wrote:why are you running GAs from a test build of VirtualBox? Generally speaking, having GAs from a later version of the software is a big no-no.

To try the test build GAs, you'd also install the test build of Virtualbox.

Looks like this one was missed:

mpack wrote:max out graphics RAM.

old log wrote:00:00:03.953213 VRamSize <integer> = 0x0000000004000000 (67 108 864, 64 MB)

new log wrote:00:00:03.417527 VRamSize <integer> = 0x0000000004000000 (67 108 864, 64 MB)

Zorus wrote:since it does not start anymore

Since the VM used to work, this might possibly be a CentOS problem, which could be since Hyper-V the big Virtualbox blocker on Windows hosts is gone.

Please try making a new CentOS VM, to see if Virtualbox is running. If the new VM works, then the old VM's OS may have a problem.

Zorus wrote:t gets stuck on the black screen with the Centos logo at the bottom.

Check if this can happen on physical computers running CentOS. If so, do to the VM what the fix for the physical computers is.

Zorus wrote:I would like to retrieve an nginx configuration file

You can attach the VM's drive to another VM that can understand the drive's file system and get the file off. On Windows hosts, 7-zip can open the drive file on some Linux OS's and allow extracting files to the Windows host.

Hi,
i don't understand what to do about the "Test-build Guest Additions" ??

I tried another CentOS8 VM that i had, and I have no problem it started correctly up to the login interface.

I put the maximum graphics memory (128Mb instead of 64 Mb), but the probleme it still there...

I tried to open the file "CentOs8.vdi" On Windows with 7-zip, but i see 2 files : 0.img and 1.lvm, which one contains my data ?

Zorus wrote: i don't understand what to do about the "Test-build Guest Additions" ??

Reinstall Guest Additions following the instructions in the user manual chapter 4. Don't do anything the instructions didn't tell you to do, for example do not download a Guest Additions ISO separately. The correct GAs are bundled with the software - obviously - so I have no idea why people think otherwise.

Zorus wrote:i see 2 files : 0.img and 1.lvm, which one contains my data ?

And did you try to open either of these?

You have to exert some energy here.

Hi,

finally I used powerIso to open "CentOs8.vdi" and I managed to recover all the files I wanted

Thanks for your help

Great! Glad you got your data.