error: Loaded libraries ("/etc/emacs/site-start.d/50ess.el") depend on /usr/share/emacs25/site-lisp/ess/ess-site.elc

[Manuel López-Ibáñez]

error: Loaded libraries ("/etc/emacs/site-start.d/50ess.el") depend on /usr/share/emacs25/site-lisp/ess/ess-site.elc

This seems to come from an install error:
ERROR:ess-etc-directory
Relative to ess-lisp-directory, one of the following must exist:
../etc/ess, ../etc, ../../etc/ess or ./etc

This bug is fixed in Debian:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=882042

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ess 17.11-2
ProcVersionSignature: Ubuntu 4.18.0-15.16~18.04.1-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Feb 26 13:52:29 2019
InstallationDate: Installed on 2019-02-23 (2 days ago)
InstallationMedia: Kubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210)
PackageArchitecture: all
SourcePackage: ess
UpgradeStatus: No upgrade log present (probably fresh install)