It looks like your /boot partition has run out of space. You will want to remove old kernels ('sudo apt remove linux-image-<some version>') then run 'sudo apt -f install' to finish the installation.
** 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/1744910 Title: package grub-pc 2.02~beta2-36ubuntu3.14 failed to install/upgrade: sub-processo script post-installation instalado retornou estado de saída de erro 4 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1744910/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs