Gfilui

Yesterday I upgraded distro and today when I am using apt-get to install anything or to update, I get an error:

N: Ignoring file '50unattended-upgrades.ucf-dist' in directory '/etc/apt/apt.conf.d/' as it has an invalid filename extension

As far as I know, this error occurs when some new configs/settings are mixed with the old ones. So I tried to debug it by moving to the folder ls -l /etc/apt/apt.conf.d/

total 52
-rw-r--r-- 1 root root 82 May 19 07:59 00CDMountPoint
-rw-r--r-- 1 root root 40 May 19 07:59 00trustcdrom
-rw-r--r-- 1 root root 769 Sep 2 23:56 01autoremove
-r--r--r-- 1 root root 1936 Sep 25 11:56 01autoremove-kernels
-rw-r--r-- 1 root root 628 Jan 4 2015 01autoremove-postgresql
-rw-r--r-- 1 root root 202 Sep 13 02:17 20listchanges
-rw-r--r-- 1 root root 1040 Dec 9 2014 20packagekit
-rw-r--r-- 1 root root 1438 Sep 16 16:46 50appstream
-rw-r--r-- 1 root root 3945 Jun 29 2015 50unattended-upgrades
-rw-r--r-- 1 root root 4072 Sep 24 19:57 50unattended-upgrades.ucf-dist
-rw-r--r-- 1 root root 182 Mar 19 2015 70debconf
-rw-r--r-- 1 root root 142 Oct 6 2014 80debtags

Looks like the file 50unattended-upgrades.ucf-dist is present. Now my question is if I use rm 50unattended-upgrades.ucf-dist then would it cause any fatalities ahead? I am a bit afraid to use rm here, as the extension is ucf-dist . I researched on the internet and public forums and people were writing about using gconf-cleaner, but haven't tried!

Update 1: As suggested in comment, I am putting the output of cat 50unattended-upgrades.ucf-dist

// Unattended-Upgrade::Origins-Pattern controls which packages are
// upgraded.
//
// Lines below have the format format is "keyword=value,...". A
// package will be upgraded only if the values in its metadata match
// all the supplied keywords in a line. (In other words, omitted
// keywords are wild cards.) The keywords originate from the Release
// file, but several aliases are accepted. The accepted keywords are:
// a,archive,suite (eg, "stable")
// c,component (eg, "main", "crontrib", "non-free")
// l,label (eg, "Debian", "Debian-Security")
// o,origin (eg, "Debian", "Unofficial Multimedia Packages")
// n,codename (eg, "jessie", "jessie-updates")
// site (eg, "http.debian.net")
// The available values on the system are printed by the command
// "apt-cache policy", and can be debugged by running
// "unattended-upgrades -d" and looking at the log file.
//
// Within lines unattended-upgrades allows 2 macros whose values are
// derived from /etc/debian_version:
// $distro_id Installed origin.
// $distro_codename Installed codename (eg, "jessie")
Unattended-Upgrade::Origins-Pattern 
 // Codename based matching:
 // This will follow the migration of a release through different
 // archives (e.g. from testing to stable and later oldstable).
// "o=Debian,n=jessie";
// "o=Debian,n=jessie-updates";
// "o=Debian,n=jessie-proposed-updates";
// "o=Debian,n=jessie,l=Debian-Security";

 // Archive or Suite based matching:
 // Note that this will silently match a different release after
 // migration to the specified archive (e.g. testing becomes the
 // new stable).
// "o=Debian,a=stable";
// "o=Debian,a=stable-updates";
// "o=Debian,a=proposed-updates";
 "origin=Debian,codename=$distro_codename,label=Debian-Security";
;

// List of packages to not update (regexp are supported)
Unattended-Upgrade::Package-Blacklist 
// "vim";
// "libc6";
// "libc6-dev";
// "libc6-i686";
;

// This option allows you to control if on a unclean dpkg exit
// unattended-upgrades will automatically run 
// dpkg --force-confold --configure -a
// The default is true, to ensure updates keep getting installed
//Unattended-Upgrade::AutoFixInterruptedDpkg "false";

// Split the upgrade into the smallest possible chunks so that
// they can be interrupted with SIGUSR1. This makes the upgrade
// a bit slower but it has the benefit that shutdown while a upgrade
// is running is possible (with a small delay)
//Unattended-Upgrade::MinimalSteps "true";

// Install all unattended-upgrades when the machine is shuting down
// instead of doing it in the background while the machine is running
// This will (obviously) make shutdown slower
//Unattended-Upgrade::InstallOnShutdown "true";

// Send email to this address for problems or packages upgrades
// If empty or unset then no email is sent, make sure that you
// have a working mail setup on your system. A package that provides
// 'mailx' must be installed. E.g. "user@example.com"
//Unattended-Upgrade::Mail "root";

// Set this value to "true" to get emails only on errors. Default
// is to always send a mail if Unattended-Upgrade::Mail is set
//Unattended-Upgrade::MailOnlyOnError "true";

// Do automatic removal of new unused dependencies after the upgrade
// (equivalent to apt-get autoremove)
//Unattended-Upgrade::Remove-Unused-Dependencies "false";

// Automatically reboot *WITHOUT CONFIRMATION* if
// the file /var/run/reboot-required is found after the upgrade 
//Unattended-Upgrade::Automatic-Reboot "false";

// Automatically reboot even if there are users currently logged in.
//Unattended-Upgrade::Automatic-Reboot-WithUsers "true";

// If automatic reboot is enabled and needed, reboot at the specific
// time instead of immediately
// Default: "now"
//Unattended-Upgrade::Automatic-Reboot-Time "02:00";

// Use apt bandwidth limit feature, this example limits the download
// speed to 70kb/sec
//Acquire::http::Dl-Limit "70";

See this explanation of the origin and purpose of .ucf-dist files. This means you can either ignore the notice (that's what the N: prefix stands for) or remove said file.

Before you remove the file, make sure it doesn't contain any packages you might still need. Compare it to the one that is currently active on your system:

diff /etc/apt/apt.conf.d/50unattended-upgrades.ucf-old /etc/apt/apt.conf.d/50unattended-upgrades

If you are sure you don't need anything any more, you can ignore this file or remove it. To remove the file run:

sudo rm /etc/apt/apt.conf.d/50unattended-upgrades.ucf-dist

This also happened to me when I upgraded from 14.04 to 16.04, during upgrade installation I was prompted to choose between the original (modified by me) 50unattended-upgrades file or the original one contained in the package update, I of course chose to keep the former.

After installation the uncalled for file 50unattended-upgrades.ucf-dist was present in my system, after I took a quick glance to check if there was any significant change with the old version of the file, it was plain obvious there wasn't any difference, so I simply deleted it.

Bottom line, you can just get rid of it if you're happy with your current version of 50unattended-upgrades.