package:usrmerge:24ubuntu3
Setting up usrmerge (24ubuntu3) ...

FATAL ERROR:
Both /sbin/update-grub and /usr/sbin/update-grub exist.

You can try correcting the errors reported and running again
/usr/lib/usrmerge/convert-usrmerge until it will complete without errors.
Do not install or update other Debian packages until the program
has been run successfully.

dpkg: error processing package usrmerge (--configure):
 installed usrmerge package post-installation script subprocess returned error exit status 1