My operating system: 64-bit openSUSE Leap 15.0 Linux using the Lightweight X Windows System, version 11 (X11) Desktop Environment (LXDE) in Oracle Virtual Machine (VM) VirtualBox 5.2.18 r124319 (Qt5.6.2) (VirtualBox), with VirtualBox running within 64-bit Windows 10 Home Edition

My Windows-10 display adapter: Intel® HD Graphics 4000

My graphics adapter in VirtualBox: VGA (Video Graphics Adapter or Array) compatible controller: InnoTek Systemberatung GmbH VirtualBox Graphics Adapter (obtained via the command “lspci” as a “root” user in openSUSE using version 4.12.14-lp150.12.16.1-default of the Linux kernel)

Working Linux kernel version: 64-bit, 4.12.14-lp150.12.16.1-default
The problematic Linux kernel version for me:  64-bit, 4.12.14-lp150.12.19.2-default

VirtualBox Guest Additions were installed from openSUSE repositories.  They have gratefully been working well for me in version 4.12.14-lp150.12.16.1-default of the Linux kernel. 

On numerous “boots” into openSUSE using version 4.12.14-lp150.12.16.1-default of the 64-bit Linux kernel I saw inconsequential, virtual-console failure notices.  But on ignoring them the Plymouth login screen could gratefully successfully be reached.  But after I upgraded the Linux kernel to version 4.12.14-lp150.12.19.2-default of it on October 8, 2018 and tried to “boot” into openSUSE using that kernel version, unfortunately I could not proceed to the Plymouth login screen.  Consequently I manually forced a shutdown of the openSUSE Virtual Machine (VM) within VirtualBox.

But in /usr/lib/systemd/system/plymouth-start.service, probablyas  a “root” user while using the version 4.12.14-lp150.12.16.1-default of the Linux kernel, after changing the line

Wants=systemd-ask-password-plymouth.path system-vconsole-setup.service

to read as

Wants=systemd-ask-password-plymouth.path

and then executing 

mkinitrd

, later while using the version 4.12.14-lp150.12.19.2-default of the Linux kernel the notice of a failure associated with virtual console was eliminated; and I could at least sometimes proceed on to the Plymouth, openSUSE login screen using that updated version of the Linux kernel  (This follows l4tk’s kindly provided advice on https://forums.opensuse.org/showthread.php/532834-Failed-to-start-Setup-Virtual-Console on the Internet.).  However, I found that I could not horizontally stretch the LXDE desktop along with the window VirtualBox made available for the openSUSE VM; in other words the automatic resizing of the window for the openSUSE desktop within the VirtualBox window for the guest, openSUSE operating system did not work for me.  I forced a shutdown of the openSUSE VM within VirtualBox.

I thought that my problem might have been caused by executing the command

mkinitrd

in version 4.12.14-lp150.12.16.1-default of the Linux kernel after updating the Linux kernel to version 4.12.14-lp150.12.19.2-default of it.  But unfortunately after uninstalling version 4.12.14-lp150.12.19.2-default and 11 other old versions of the Linux kernel, and then reinstalling version 4.12.14-lp150.12.19.2-default of the Linux kernel, the automatic desktop resizing problem remained.

One obvious temporary solution for me which will allow the openSUSE desktop to be expandable to the large horizontal size allotted for it by VirtualBox is to within VirtualBox “boot” into openSUSE using the previous version 4.12.14-lp150.12.16.1-default of the Linux kernel, which I did not delete.  (After having followed the advice of poster l4tk on https://forums.opensuse.org/showthread.php/532834-Failed-to-start-Setup-Virtual-Console, the notice of a failure associated with the virtual console also gratefully did not appear using this older version of the Linux kernel.  However, that notice was never a consequential problem in that older version of the Linux kernel for me, no matter whether I followed l4tk’s advice or not.)  I am grateful to the openSUSE developers for providing the option of “booting” into openSUSE using the previous version of the Linux kernel following the condition that “booting” into openSUSE using an updated version of the Linux kernel was unsuccessful or results were undesirable for a particular configuration of computer hardware.

Possible options for the future for me: 

1) To “boot” into openSUSE using version 4.12.14-lp150.12.16.1-default of the Linux kernel.
2) To wait for a possible update of version 4.12.14-lp150.12.19.2-default of the Linux kernel which will eliminate the horizontal desktop-size limitation for me.
3) Wait for a completely new version of the Linux kernel; and then after “booting” into openSUSE using that new kernel version to see if the desktop, automatic-resizing problem is eliminated for me or not.  But if that problem would not be solved for me using that new version of the kernel, I hope that I in that case would be able to keep on using version 4.12.14-lp150.12.16.1-default of the Linux kernel, which at that time might be two versions behind the current version of the Linux kernel for openSUSE.  Or, in a figure of speech, one would prefer not to have to throw away his old pair of shoes until he sees that he is going to own a new pair of shoes which will fit his feet.