Comment # 6 on bug 1152720 from Dr. Werner Fink

I see this here frm log file

 bash> grep ^E Downloads/cups_gs927.log
 E [02/Oct/2019:16:35:36 +0200] Unable to open listen socket for address
[v1.::1]:631 - Cannot assign requested address.
 E [02/Oct/2019:16:36:05 +0200] [CGI] cups-brf must be called as root
 E [02/Oct/2019:16:36:05 +0200] [cups-deviced] PID 20167 (cups-brf) stopped
with status 1!
 E [02/Oct/2019:16:36:05 +0200] [cups-deviced] PID 20172 (gutenprint52+usb)
stopped with status 1!
 E [02/Oct/2019:16:36:15 +0200] [Job 221] Job stopped due to filter errors;
please consult the error_log file for details.

the question rises if this cause the messages also included in the log file and
seen in comment#2