Downloaded https://download.freebsd.org/releases/ISO-IMAGES/14.0/FreeBSD-14.0-RELEASE-amd64-dvd1.iso and attempted to boot via virtualbox on Windows10. Without efi box checked, the boot process displays: "FATAL: Cound not read from the boot medium! System halted" or with the efi box checked, I'm unable to exit the startup.nsh loop. Earlier I tried the i386-bootonly.iso on a VirtualBox i386, with the same result. Notes: 1. that I have 6 VM's running FBSD 12.4S on this desktop and 1 running 13.2S which I used to build 14.0-releng (I'm continuing to research different problems there). 2. Virtualbox is used for testing prior to installing on bare metal devices, but unlike https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275326 we don't seem to get past loader stage (via the FreeBSD provided iso). There must be information about talking to the iso boot media but...
Just tested: 1. Installation media FreeBSD-14.0-RELEASE-amd64-disc1.iso FreeBSD-14.0-RELEASE-amd64-dvd1.iso 2. EFI and non-EFI. 3. VirtualBox 6.1.50 on host FreeBSD 13.2-p9 amd64. All 4 options boot without errors. P.S. I'm using virtual SAS controller.
Can you provide some info about the system that you're running virtualbox on? Perhaps there's some relevant difference.
I also tried installing FreeBSD 14 in VirtualBox on Windows and could not reproduce a problem, https://mastodon.social/@emaste/111296195313874246