Hi there,

Today I spent hours figuring out why my ubuntu machine was not resizing automatically when I would resize the window.

I have a windows laptop running virtual box with ubuntu 20 and I did an update on the ubuntu machine, after the update crashed, the resize would not work.

after troubleshooting, I figured out the the following settings on onther machine worked.

These are the settings that work for me on this image.

hope that helps.

Fix Auto-resize Guest Display Disabled In Ubuntu Virtualbox 6