I am using LibreOffice 6.0.2~rc1-0ubuntu0.16.04.1~lo1 from the LO PPA.
1. Start Writer
2. Go to Tools > Options > Language Settings > Languages
3. Enable Complex text layout (choose any language)
4. Save & close Options and open it again
5. Go to Tools > Options > Language Settings > Complex Text Layout
6. A message appears with "Currently auto-detection and installation of missing fonts is not supported."
ProblemType: Crash
DistroRelease: Ubuntu 16.04
Package: sessioninstaller 0.20+bzr150-0ubuntu4.1
ProcVersionSignature: Ubuntu 4.4.0-116.140-generic 4.4.98
Uname: Linux 4.4.0-116-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Mar 26 12:50:38 2018
ExecutablePath: /usr/bin/session-installer
InstallationDate: Installed on 2017-06-21 (277 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
InterpreterPath: /usr/bin/python3.5
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/bin/session-installer
PythonArgs: ['/usr/bin/session-installer']
SourcePackage: sessioninstaller
Title: session-installer crashed with sessioninstaller.errors.ModifyInternalError in _install_fontconfig_resources(): org.freedesktop.Packagekit.Modify.InternalError: Currently auto-detection and installation of missing fonts is not supported.
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip libvirtd lpadmin plugdev sambashare sudo
Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1651686, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.