> /usr/sbin/grub-mkconfig: 12: /etc/default/grub: quiet: not found
> run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127
This indicates an incorrect manual edit of /etc/default/grub that has broken the syntax of the file - not a bug in the grub package. You will need to fix this file so that it declares variables using correct shell syntax (no spaces around equal signs; quotes around any values that contain spaces).
The error in the logs is:
> /usr/sbin/ grub-mkconfig: 12: /etc/default/grub: quiet: not found postinst. d/zz-update- grub exited with return code 127
> run-parts: /etc/kernel/
This indicates an incorrect manual edit of /etc/default/grub that has broken the syntax of the file - not a bug in the grub package. You will need to fix this file so that it declares variables using correct shell syntax (no spaces around equal signs; quotes around any values that contain spaces).