SUMMARY
After two days I upgraded Debian 9 to 10 on this computer, it give me this problem. My Display Manager is XDM and when i try to login with any credentials, it crashes and reopens a bugged session of XDM. When i used Debian 9, I never had this problem.

Journalctl

kernel: plasmashell[4408]: segfault at 0 ip 00007f29428b3768 sp 00007fff9a7fd880 error 4 in libkcupslib.so[7f294288a000+31000]
kernel: Code: <some-numbers>

STEPS TO REPRODUCE
1. Open a session of the Display Manager (XDM)
2. Login

OBSERVED RESULT
Initially it tries to load the desktop, but after some seconds it is replaced by a black screen and after that a bugged session of XDM is loaded.

EXPECTED RESULT
Correct loading of desktop environment

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Linux 4.19.0-5-amd64 (Debian 10 Buster)
KDE Plasma Version: 5.14.5
KDE Frameworks Version: 5.54.0
Qt Version: 5.11.3
dpkg -l | grep xdm
XDM version: 1.1.11-3

ADDITIONAL INFORMATION
Seems like if I clean the print queue the bug disappears. I had something like this:

lpstat -o
PRINTER_NAME1-4476 user2 236861440   ven 04 nov 2016 13:00:19 CET
PRINTER_NAME1-4476 user2 236861440   ven 04 nov 2016 13:00:19 CET
PRINTER_NAME2-4824  user3               1024   lun 02 jan 2017 09:15:44 CET
PRINTER_NAME2-4824  user3               1024   lun 02 jan 2017 09:15:44 CET
PRINTER_NAME1-5357 user2  2314240   ven 17 feb 2017 09:28:59 CET
PRINTER_NAME1-5357 user2  2314240   ven 17 feb 2017 09:28:59 CET
PRINTER_NAME1-5358 user2  2314240   ven 17 feb 2017 09:39:24 CET
PRINTER_NAME1-5358 user2  2314240   ven 17 feb 2017 09:39:24 CET
PRINTER_NAME1-5359 user2  2314240   ven 17 feb 2017 09:41:49 CET
PRINTER_NAME1-5359 user2  2314240   ven 17 feb 2017 09:41:49 CET

and removed with cancel -a PRINTER_NAME1 and cancel -a PRINTER_NAME2

After that, i was able to log in correctly again.