Hello.

I have encoutered this bug today.

Confirming that the removing of print-manager solves it.
In case it helps, I printed today to a non-existing printer. (Or not connected now)
This might be the reason.

System info:
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$ uname -a
Linux xxxxxx 4.15.0-32-generic #35-Ubuntu SMP Fri Aug 10 17:58:07 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
===================================
$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.1 LTS"
===================================


===================================
$ cat /var/log/syslog | grep libkcups
Aug 23 19:09:40 xxxx kernel: [   21.796551] plasmashell[2806]: segfault at 0 ip 00007f06228bf556 sp 00007ffda5944a00 error 4 in libkcupslib.so[7f0622883000+55000]
Aug 23 19:11:58 xxxx kernel: [  159.541136] plasmashell[3142]: segfault at 0 ip 00007fb9f90eb556 sp 00007ffd1f9dc550 error 4 in libkcupslib.so[7fb9f90af000+55000]
Aug 23 19:12:24 xxxx kernel: [  185.479028] plasmashell[3190]: segfault at 0 ip 00007fe7ae4b3556 sp 00007ffddf141da0 error 4 in libkcupslib.so[7fe7ae477000+55000]
Aug 23 19:13:20 xxxx kernel: [  241.740921] plasmashell[3907]: segfault at 0 ip 00007f90b4e6e556 sp 00007fff15942bc0 error 4 in libkcupslib.so[7f90b4e32000+55000]
Aug 23 19:17:15 xxxx kernel: [   21.434726] plasmashell[2561]: segfault at 0 ip 00007f679fd09556 sp 00007ffcfd0279a0 error 4 in libkcupslib.so[7f679fccd000+55000]
Aug 23 19:25:00 xxxx kernel: [  486.744808] plasmashell[19246]: segfault at 0 ip 00007f35a96d5556 sp 00007fff5621e720 error 4 in libkcupslib.so[7f35a9699000+55000]
Aug 23 19:30:31 xxxx kernel: [  817.724261] plasmashell[23856]: segfault at 0 ip 00007fbc4b29d556 sp 00007ffe87f7e930 error 4 in libkcupslib.so[7fbc4b261000+55000]
Aug 23 19:31:22 xxxx kernel: [  868.486032] plasmashell[24483]: segfault at 0 ip 00007f10fc9b2556 sp 00007ffe7b7f9890 error 4 in libkcupslib.so[7f10fc976000+55000]
======================================

$ dpkg -l | egrep "plasma"
rc  kdeconnect-plasma                               1.3.1-0ubuntu0.1                            all          Transitional package (kdeconnect-plasma -> kdeconnect)
ii  kdeplasma-addons-data                           4:5.12.6-0ubuntu0.1                         all          locale files for kdeplasma-addons
ii  libkdeclarative5                                4:4.14.38-0ubuntu3                          amd64        declarative library for plasma
ii  libkf5plasma5:amd64                             5.44.0-0ubuntu3                             amd64        Plasma Runtime components
ii  libkf5plasmaquick5:amd64                        5.44.0-0ubuntu3                             amd64        Plasma Runtime components
ii  libplasma-geolocation-interface5                4:5.12.6-0ubuntu0.1                         amd64        Plasma Workspace for KF5 library
ii  libplasma3                                      4:4.14.38-0ubuntu3                          amd64        Plasma Library for the KDE Platform
ii  plasma-dataengines-addons                       4:5.12.6-0ubuntu0.1                         amd64        additional data engines for Plasma
ii  plasma-desktop                                  4:5.12.6-0ubuntu0.1                         amd64        Tools and widgets for the desktop
ii  plasma-desktop-data                             4:5.12.6-0ubuntu0.1                         all          Tools and widgets for the desktop data files
ii  plasma-discover                                 5.12.6-0ubuntu0.1                           amd64        Discover software management suite
ii  plasma-discover-common                          5.12.6-0ubuntu0.1                           all          Discover software manager suite (common data files)
rc  plasma-discover-private                         5.6.2-1ubuntu1.1                            amd64        Private runtime libraries for the Discover suite
ii  plasma-framework                                5.44.0-0ubuntu3                             amd64        Plasma Runtime components
ii  plasma-integration                              5.12.6-0ubuntu0.1                           amd64        Qt Platform Theme integration plugins for KDE Plasma
ii  plasma-look-and-feel-org-kde-breezedark-desktop 4:5.12.6-0ubuntu0.1                         all          Dark Breeze look-and-feel for Plasma
ii  plasma-nm                                       4:5.12.6-0ubuntu0.1                         amd64        Plasma5 networkmanager library.
ii  plasma-pa                                       4:5.12.6-0ubuntu0.1                         amd64        Plasma 5 Volume controller
ii  plasma-runners-addons                           4:5.12.6-0ubuntu0.1                         amd64        additional runners for Plasma 5 and Krunner
ii  plasma-scriptengine-javascript                  4:17.08.3-0ubuntu1                          amd64        JavaScript script engine for Plasma
ii  plasma-vault                                    5.12.6-0ubuntu0.1                           amd64        Plasma applet and services for creating encrypted vaults
ii  plasma-wallpapers-addons                        4:5.12.6-0ubuntu0.1                         amd64        additional wallpaper plugins for Plasma 5
ii  plasma-widgets-addons                           4:5.12.6-0ubuntu0.1                         amd64        additional widgets for Plasma 5
ii  plasma-workspace                                4:5.12.6-0ubuntu0.1                         amd64        Plasma Workspace for KF5
===================================