cups installed and did work well for long, no idea when stopped working
Since sending something to printer wasn't possible, I removed the network printer, tried to add it again with no success
from System --> Print Settings --> add IP select IPP--> cups server error
if I try through the web page --> http://localhost:631/help/network.html --> Not found
Here some output that might help
~ $ sudo systemctl status cups.service
[sudo] password for werner:
● cups.service - CUPS Scheduler
Loaded: loaded (/lib/systemd/system/cups.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2019-11-21 11:42:22 -03; 4h 43min ago
Docs: man:cupsd(8)
Main PID: 480 (cupsd)
Tasks: 1 (limit: 4915)
Memory: 8.2M
CGroup: /system.slice/cups.service
└─480 /usr/sbin/cupsd -l
~ $ sudo journalctl | grep cups
Nov 21 11:42:22 C75D audit[453]: AVC apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/cups-browsed" pid=453 comm="apparmor_parser"
Nov 21 11:42:22 C75D kernel: audit: type=1400 audit(1574347342.730:8): apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/cups-browsed" pid=453 comm="apparmor_parser"
Nov 21 11:42:22 C75D audit[451]: AVC apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/lib/cups/backend/cups-pdf" pid=451 comm="apparmor_parser"
Nov 21 11:42:22 C75D audit[451]: AVC apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/cupsd" pid=451 comm="apparmor_parser"
Nov 21 11:42:22 C75D audit[451]: AVC apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/cupsd//third_party" pid=451 comm="apparmor_parser"
Nov 21 15:59:01 C75D sudo[2685]: werner : TTY=pts/0 ; PWD=/home/werner ; USER=root ; COMMAND=/etc/init.d/cups start
Nov 21 16:06:01 C75D sudo[2840]: werner : TTY=pts/0 ; PWD=/home/werner ; USER=root ; COMMAND=/usr/bin/systemctl status cups.service
Nov 21 16:15:12 C75D polkitd(authority=local)[510]: Operator of unix-session:2 successfully authenticated as unix-user:werner to gain TEMPORARY authorization for action org.opensuse.cupspkhelper.mechanism.all-edit for unix-process
1636776 [/usr/bin/python3 /usr/share/system-config-printer/system-config-printer.py] (owned by unix-user:werner)Nov 21 16:15:15 C75D cups-pk-helper-[3168]: g_variant_new_array: assertion 'child_type == NULL || g_variant_type_is_definite (child_type)' failed
Nov 21 16:15:15 C75D kernel: traps: cups-pk-helper-[3168] trap int3 ip:7faac7649c75 sp:7fff198e7f00 error:0 in libglib-2.0.so.0.5800.3[7faac7611000+7e000]
Nov 21 16:15:15 C75D cups-pk-helper-[3168]: g_variant_get_type: assertion 'value != NULL' failed
Nov 21 16:15:15 C75D cups-pk-helper-[3168]: g_variant_type_is_subtype_of: assertion 'g_variant_type_check (type)' failed
Nov 21 16:15:15 C75D cups-pk-helper-[3168]: g_variant_get_type_string: assertion 'value != NULL' failed
Nov 21 16:15:15 C75D cups-pk-helper-[3168]: g_variant_new: expected GVariant of type 'a{ss}' but received value has type '(null)'
Nov 21 16:26:07 C75D sudo[3347]: werner : TTY=pts/0 ; PWD=/home/werner ; USER=root ; COMMAND=/usr/bin/systemctl status cups.service
Nov 21 16:28:11 C75D polkitd(authority=local)[510]: Operator of unix-session:2 successfully authenticated as unix-user:werner to gain TEMPORARY authorization for action org.opensuse.cupspkhelper.mechanism.all-edit for unix-process
1636776 [/usr/bin/python3 /usr/share/system-config-printer/system-config-printer.py] (owned by unix-user:werner)Nov 21 16:28:13 C75D cups-pk-helper-[3367]: g_variant_new_array: assertion 'child_type == NULL || g_variant_type_is_definite (child_type)' failed
Nov 21 16:28:13 C75D kernel: traps: cups-pk-helper-[3367] trap int3 ip:7f32ac4e2c75 sp:7ffdd5ca9850 error:0 in libglib-2.0.so.0.5800.3[7f32ac4aa000+7e000]
Nov 21 16:28:13 C75D cups-pk-helper-[3367]: g_variant_get_type: assertion 'value != NULL' failed
Nov 21 16:28:13 C75D cups-pk-helper-[3367]: g_variant_type_is_subtype_of: assertion 'g_variant_type_check (type)' failed
Nov 21 16:28:13 C75D cups-pk-helper-[3367]: g_variant_get_type_string: assertion 'value != NULL' failed
Nov 21 16:28:13 C75D cups-pk-helper-[3367]: g_variant_new: expected GVariant of type 'a{ss}' but received value has type '(null)'
~ $ ps -aux | grep cups
root 480 0.0 0.0 29212 7724 ? Ss 11:42 0:00 /usr/sbin/cupsd -l
root 505 0.0 0.0 185184 11104 ? Ssl 11:42 0:00 /usr/sbin/cups-browsed
werner 3448 0.0 0.0 6076 888 pts/0 S+ 16:35 0:00 grep cups