I was running Virtual Box 5.2.22 under Ubuntu 16.04. After my employer updated the kernel, VB ceased to work (kernel modules). After following the instructions provided by the error message, I thought I'd try a newer version of VB. I installed 6.0.8.

VB 6.0.8 solved the problem but now I have a problem with very small text size on the VirtualBox "control" window on a 2560x1440 display. If I try a 1920x1080 screen, the text is "normal" size but that isn't a viable long term solution.

When I launch a Guest O/S the title bar is fine and the guest O/S works fine. The text size inside the Guest O/S is fine. However, the VB menu bar in that window is small. (The guest O/S versions that I tested are Ubuntu 16.04 and 18.04 as well as CentOS 7.6.)

Every other program that I've run on this computer has text that I can read. So far, it is just VirtualBox 6.0.8.

I found one page that suggested I increase the scaling size to 200% but that changed the scaling size inside the Guest O/S; not for the VB menus. I didn't find a control for the menu size. Attempting to change the scale for Title and Menu bars in the Host O/S worked had the expected effect on other programs but not on VirtualBox.


You can use a different theme or a different stylesheet to setup the theme in per application basis, try one of the following commands and check what's working:

VirtualBox --style "Adwaita"
env QT_STYLE_OVERRIDE=Adwaita VirtualBox --style "Adwaita"
env QT_QPA_PLATFORMTHEME=gtk3 VirtualBox
VirtualBox -style Adwaita -stylesheet /Path-to-custom/color-scheme-qt/dark.qss

Update your .desktop file to run VirtualBox with a custom command

  • Unfortunately, none of these solved the problem. However, your post was useful because it encouraged me to research styles and themes for VirtualBox. It might be that VB 6.0.8 under Ubuntu 16.04 isn't honoring theme/style requests at my resolution. – Hugh McCurdy May 28 at 13:18

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