sddm crashed with SIGABRT in QMessageLogger::fatal()

[emk2203]

directly after startup of computer; no problems in operation, login possible, no visible signs of crash

ProblemType: Crash
DistroRelease: Ubuntu 18.10
Package: sddm 0.18.0-1ubuntu2
ProcVersionSignature: Ubuntu 4.18.0-8.9-generic 4.18.7
Uname: Linux 4.18.0-8-generic x86_64
ApportVersion: 2.20.10-0ubuntu11
Architecture: amd64
Date: Thu Sep 20 23:24:37 2018
ExecutablePath: /usr/bin/sddm
ProcCmdline: /usr/bin/sddm
ProcEnviron:
 LANG=de_DE.UTF-8
 LC_MESSAGES=POSIX
 PATH=(custom, no user)
Signal: 6
SourcePackage: sddm
StacktraceTop:
 QMessageLogger::fatal(char const*, ...) const () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
 ?? ()
 SDDM::Seat::createDisplay(int) ()
 SDDM::Seat::Seat(QString const&, QObject*) ()
 SDDM::SeatManager::createSeat(QString const&) ()
Title: sddm crashed with SIGABRT in QMessageLogger::fatal()
UpgradeStatus: Upgraded to cosmic on 2017-06-03 (474 days ago)
UserGroups:

[Apport retracing service (apport)]

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 #1711889, 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.