Kernel panic - not syncing: Attempted to kill init! exitcode=0x00007f00

[Valerio Vanni]

https://bugzilla.kernel.org/show_bug.cgi?id=217083

I got this error after upgrading a Debian machine (x86-64) from Stretch 
to Buster. Upgrade is successful, but the next boot it crashes.

The machine is an Asus B360M-A with an Intel i7-8700 CPU and 16GB DDR4.
My kernel is 4.20.17 (from kernel.org, not a distribution kernel), but I 
tried with 4.19.273 and 5.10.169 with the same .config.