As per Jason’s comment, with a new ILO4 update HP apparently has fixed an issue related to booting from SD cards. Whether this is the same issue is unclear though since the original KB article I linked to has not been updated.
Important note: The general symptom of such a Red Screen of Death described here is NOT specific to ESXi or booting from SD cards in general. It can happen with Windows, Linux or any other OS as well as other boot media such as normal disks/RAID arrays, if the server has a problem booting from this device (broken boot sector/partition/boot loader etc).
A couple of weeks ago I was updating a few HP Proliant DL360p Gen8 servers running ESXi on a local SD card with ESXi patches via VUM, so business as usual. Almost, because on one of the servers I ran into the following issue:
After rebooting the host, the BIOS POST completed fine and the Proliant DL360p Gen8 server should now boot the ESXi OS from it’s attached USB SD card where ESXi was installed; but instead it displayed this unsightly screen telling something went very, very wrong:
I reset the server several times via iLO but the issue persisted and I had no idea what exactly went bonkers here. Then I decided to boot a Linux live image, which worked fine, narrowing down the issue to the OS installation (device) itself. I thought the updates corrupted the installation but that actually wasn’t the case.
When attempting to mount the SD card USB drive from within the live Linux I noticed it was actually completely absent from the system. The USB bus was still ok, but lsusb showed no SD card reader device in the system at all!