Confirmed on KDE Neon 5.15.1. Might be due to a network printer which was recognized automatically but now no longer exists. The fixes mentioned above (uninstalling the print-manager) appears to work.
[ 5748.844786] plasmashell[10378]: segfault at 0 ip 00007f9c5c597a50 sp 00007ffd24d6a2f0 error 4 in libkcupslib.so[7f9c5c557000+56000] Also my logs indicate that this might be related to an AppArmor issue with the /usr/sbin/cupsd profile. There are multiple denied entries in the logs whichof I have appended one. Afterwards there is the segfault in libkcupslib. syslog:Feb 26 18:55:13 matteo-whatever kernel: [ 5090.165402] audit: type=1400 audit(1551203713.010:42): apparmor="DENIED" operation="file_lock" profile="/usr/sbin/cupsd" name="/run/utmp" pid=1420 comm="cupsd" requested_mask="k" denied_mask="k" fsuid=0 ouid=0 syslog:Feb 26 18:58:11 matteo-whatever kernel: [ 5268.663312] plasmashell[4392]: segfault at 0 ip 00007f1ee3c3ea50 sp 00007ffdafee0690 error 4 in libkcupslib.so[7f1ee3bfe000+56000] After reinstalling the logs have changed and the "denied" entries have been changed into "allowed": syslog:Feb 26 19:06:11 matteo-whatever kernel: [ 5748.809771] audit: type=1400 audit(1551204371.662:52): apparmor="ALLOWED" operation="capable" profile="/usr/sbin/cupsd" pid=1420 comm="cupsd" capability=12 capname="net_admin" My system: Operating System: KDE neon 5.15 KDE Plasma Version: 5.15.1 KDE Frameworks Version: 5.55.0 Qt Version: 5.12.0 Kernel Version: 4.15.12-041512-generic OS Type: 64-bit Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz Memory: 15.5 GiB of RAM -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1770044 Title: plasmashell crashes on login - so I can't use my desktop system. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/plasma-workspace/+bug/1770044/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs