You have a third party package installed that has installed a broken program: /etc/grub.d/bin/grubcfg_proxy. You will need to remove it.
** Changed in: grub2 (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1637975 Title: package grub-pc 2.02~beta2-36ubuntu3.2 failed to install/upgrade: subprocess installed post-installation script returned error exit status 127 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1637975/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs