I have installed epson-inkjet-printer-escpr (yay -S epson-inkjet-printer-escpr), and selected the ppd file with the file chooser so there shouldn’t be a problem with typos or it not existing, the permissions look sensible:
ls -l /usr/share/ppd/epson-inkjet-printer-escpr/Epson-ET-2850_Series-epson-escpr-en.ppd
-rw-r--r-- 1 root root 157810 Jun 3 10:57 /usr/share/ppd/epson-inkjet-printer-escpr/Epson-ET-2850_Series-epson-escpr-en.ppd
I tried accessing it via localhost:631 in Firefox, and although the URL was initially shown as a random (and variable) string of non-printable characters, pasting the printer URL from the control centre into the printer address box, allowed me to continue.
I was then able to select the driver and get the printer working, albait with a warning:
Note:Printer drivers and raw queues are deprecated and will stop working in a future version of CUPS.
Lets say it’s not wholly satisfactory but it seem to have worked.
Thanks, that is what I expected too, but KDE control centre only offered 2 drivers, both for (IIRC) 3900 series laser printers. As I said above, using the browser did find the driver. Come to think of it, I think I’ve had similar issues before where I could only add printers via the browser and not the control centre—I’d forgotten about it as the previous printer lasted 8 years before deciding that it would not recognize any ink cartridges at all.