I'm not entirely sure what you're experiencing here. Note that this file is a conffile, so removing it is a local configuration choice that will be preserved during upgrades or reinstalls. The only way to restore a removed conffile from my understanding is purging and reinstalling the package.
** Changed in: apt (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/1766310 Title: apt-get install memtest86+ fails to create /etc/grub.d/20_memtest86+ Status in apt package in Ubuntu: Incomplete Bug description: Removing/purging the file and/or using --reinstall options do not help. Removing the file and installing it with dpkg -i /var/cache/apt/archives/memtest86+_5.01-3ubuntu2_amd64.deb works. When calling dpkg --verify on the apt-installed package, the missing file is flagged. I have no idea what causes this. The file name ending in + maybe? But wouldn't apt call dpkg for installation anyway? ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: apt 1.6.1 ProcVersionSignature: Ubuntu 4.15.0-15.16-lowlatency 4.15.15 Uname: Linux 4.15.0-15-lowlatency x86_64 ApportVersion: 2.20.9-0ubuntu6 Architecture: amd64 Date: Mon Apr 23 19:15:11 2018 InstallationDate: Installed on 2011-10-14 (2383 days ago) InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111011) SourcePackage: apt UpgradeStatus: Upgraded to bionic on 2018-01-23 (90 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1766310/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp