For those of you using my Raspberry PI Network Boot Guide, please be aware of an issue with the current raspberrypi-bootloader package (Version: 1:1.20210727-1). Here are the offending package details, though the bug may exist in one of this package’s dependencies. Here’s the offending package’s details.

Installing this package will trigger kernel panics on the Raspberry Pi 3B+, but not on 4B. I’ve not tried it on earlier hardware iterations capable of network boot, so backup before attempting an update. You can track the progress of the issue here on GitHub. If you wish to use the latest RPi Linux Kernel (5.10.52), it is compatible with the earlier version of raspberrypi-bootloader (Version: 1:1.20210527-1).