I have installed a new kernel on my root with the grsecurity and pax patches.
After installing the new kernel, grub is not working correctly any more.
It seems that pax conflicts with some programs of grub.
Thanks to the following article (https://dustri.org/b/grsec-and-grub.html), a solution was found:
Install the paxctl tool:
apt-get install paxctl
Call the tool with the following parameters:
paxctl -Cpms /usr/sbin/grub-mkdevicemap
paxctl -Cpms /usr/sbin/grub-probe
paxctl -Cpms /usr/bin/grub-mount
paxctl -Cpms /usr/bin/grub-script-check
The parameters are listed in the following article:
Maybe the -c and -z switch like stated in the dustri article also work, but
I used the -Cpms and that did the trick for me.