The warning about not being able to convert color input into grayscale
is principally no problem for you, as monochrome PostScript printers can
receive color input without any problems, they convert the input by
themselves.
What this warning tells to me is that you upgraded from a cups-filters
version from before the fix of this issue
https://github.com/OpenPrinting/cups-filters/issues/169
PS Level 1 forced for grayscale PDF rendering with Poppler/Cairo
to one afterwards.
Without the fix of this issue your printer had most probably received
PostScript Level 1 and happily printed it.
Now it is receiving PostScript Level 2.
Brother PostScript printers are known to have many bugs in their
PostScript interpreters and therefore we have already a big bunch of
workarounds in our pdftops filter.
Probably the best is to try to print without using PostScript. When
creating a print queue and selecting your printer's make, model, and
driver manually, have a look at PCL 6/XL (pxlmono) or PCL 5e
(ljet4/ljet4d/hpcups/hpijs) options.
Or try running the command
driverless
If it lists a URI (Unified Resource Identifier) for your printer
(contains your printers host name, IP, or make/model), try to set up
your printer with
lpadmin -p Printers -E -v URI -m everywhere
replacing URI by your printer's URI from the "driverless" output.
Does this work?
Till
