I have solved this. The problem was that Lexmark Optra E310 printer is not supported by Gutenprint project, so the CUPS/Gutenprint system automatically installs a driver for the Lexmark Optra E321, that is a very different printer and it works, or not, depending on document or other circumstances.
The solution was install the original PPD file made for the Optra E310 printer by Lexmark. I attach the file with this message in case it can be helpful for someone with the same problem. Greetings. ** Attachment added: "Original Lekmark Optra E310 PPD file" https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1759921/+attachment/5101051/+files/lope310.ppd -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1759921 Title: Problem with Lexmark Optra E310: printing system doesn't work To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1759921/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
