can't install ubuntu-desktop

[ironmikezero]

Ubuntu 16.04LTS - routine (daily) updater attempt failed.
Msg - can't install ubuntu-desktop report bug via terminal ubuntu-bug ubuntu-release-upgrader-core

Normally, daily checking (at beginning/end of 8-12 hour session) for updates runs smoothly. Today, not so much (error msg & reporting instructions as above).

I don't know if this is a security vulnerability or not; but, I'm not a trusting soul . . . okay, maybe a little bit paranoid.

I'm not tech savvy in the least; ergo, I'm lost.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.23
ProcVersionSignature: Ubuntu 4.4.0-112.135-generic 4.4.98
Uname: Linux 4.4.0-112-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Thu Feb 15 17:30:50 2018
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: No upgrade log present (probably fresh install)
VarLogDistupgradeTermlog: