r1soft get-module segmentation fault

When installing r1soft kernel module, I got the following error

root@localhost:~# serverbackup-setup --get-module
Failed to find headers at `/lib/modules/4.19.0-20-amd64/build`.
Get module failed.
Falling back to old get-module ...
signal: segmentation fault
root@localhost:~# 

This was on a Debian server with 4.19.0-20-amd64 kernel.

root@localhost:~# uname -a
Linux localhost 4.19.0-20-amd64 #1 SMP Debian 4.19.235-1 (2022-03-17) x86_64 GNU/Linux
root@localhost:~# uname -r
4.19.0-20-amd64
root@localhost:~#

To fix the error message, install linux-headers package.

apt install linux-headers-4.19.0-20-amd64

See r1soft backup