Run both: VBoxManage setextradata 'macosx' 'CustomVideoMode1' '1366x768x32' Custom Resolution example for a 1366x768 screen: The answer is in the manuals (whenever well-documented), always. Fortunately, you've already done some work for us and I'm sure those hours were well spent! I had the same problem as you, but I was too lazy to look for a solution for it. I just realized there is an answer my question option at the end. Forgive me if I'm completely off the mark, this is my first time using virtual box properly. I am assuming it has to do with creating your own standard resolution, and only then can you use that resolution? Anyone confirming would be nice. So, I found this and created a custom mode through the following: VBoxManage setextradata 'vmname again' 'CustomVideoMode1' '1366x768x32'Īfter doing so, I tried again, to put the first block of code: VBoxManage setextradata 'Whatever Your Machine Is Called– vmname, put in these quotes' 'VBoxInternal2/EfiGraphicsResolution' '1366x768' It wasn't supported as a standard resolution. I found this after a while, and it is probably why it didn't work. It only worked for certain standard resolutions where 1366x768 is not a part of. NOW, I've painfully tried to make this work with 1366x768, but it did NOT work (it goes to the default reso instead). After putting the code, open up your vm and hopefully reso is changed. I have also seen other tutorials instructing to use the above without putting VBoxInternal2/EfiGraphicsResolution in quotes. You should edit 1920x1080 to the resolution you need, and the name of your vm. Then you can use the code VBoxManage setextradata 'Whatever Your Machine Is Called– vmname, put in these quotes' 'VBoxInternal2/EfiGraphicsResolution' '1920x1080' cd to where your VirtualBox folder is located, I believe the default is in the C drive, but mine is put in E intentionally so you would do that by directing to the folder as such:

Run the Command Prompt as Administrator. So maybe download them if the commands to follow do not work. I do not know if VMwareTools (press X to doubt) and Virtual Box Darwin Guest Additions (this was actually specified for Mac OS X so I'm not sure) are necessary, but what I tried did not work before I downloaded them. Refer to the following Similar Forum, which did not work for me, first. Maybe someone can also explain why what I did works. I hope that others who found different solutions, especially when the solutions I tried did not work, can share theirs. This question is for people who relate to the same problems I have and spent hours searching the internet to no avail. Disclaimer- I just got this working for me in my Virtual Box 6 Big Sur guest OS version 11.1.

Virtualbox mac big sur