Daniel,

Daniel Meißner 写道：
> I am currently trying to configure my Epson printer on Guix 
> system using
> system-config-printer.  The printer is connected via USB and is
> automatically detected in the dialog window that opens if I 
> click on
> "Add". I select the printer from the list and click on 
> "Forward", then I
> enter the printer name, a description and a location in the 
> section
> "Describe Printer".  However, if I click on "Apply", the 
> following error
> message is printed:

I was unable to reproduce this at all, albeit without an Epson USB 
printer connected, of course.

My steps through the CUPS Web interface:
- Administration
- Add Printer
- Internet Printing Protocol (ipp)
  Continue
- Connection: "ipp://fake.printer/print/Print"
  Continue
- Description, Location: "test"
  Share This Printer unticked
  Continue
- Make: Epson
  Continue
- Model: EPSON ET-2600 Series , Epson Inkjet Printer Driver
         (ESC/P-R) for Linux (…)
- Then accept all default options.

Result attached.  At no point do I get an error.

Interestingly, my CUPS only ever looks in the right location for 
epson-escpr-wrapper:

--8<---------------cut here---------------start------------->8---
λ grep escpr-wrapper -a /var/log/cups/error_log 
d [03/Dec/2021:00:17:28 +0100] 
add_printer_filter(p=0x64654c639bd0(test), 
filtertype=0x64654c5b7ca0(printer/test), 
filter="application/vnd.cups-raster 0 epson-escpr-wrapper")
d [03/Dec/2021:00:17:28 +0100] test: File 
\"/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper\" 
permissions OK (040555/uid=0/gid=0).
d [03/Dec/2021:00:17:28 +0100] add_printer_filter: test: adding 
filter application/vnd.cups-raster printer/test 0 
epson-escpr-wrapper
d [03/Dec/2021:00:17:33 +0100] 
add_printer_filter(p=0x64654c639bd0(test), 
filtertype=0x64654c5b7ca0(printer/test), 
filter="application/vnd.cups-raster 0 epson-escpr-wrapper")
d [03/Dec/2021:00:17:33 +0100] test: File 
\"/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper\" 
permissions OK (040555/uid=0/gid=0).
d [03/Dec/2021:00:17:33 +0100] add_printer_filter: test: adding 
filter application/vnd.cups-raster printer/test 0 
epson-escpr-wrapper
--8<---------------cut here---------------end--------------->8---

I can even print a test page (from the Maintenance drop-down).  Of 
course it fails to connect to the printer, but still the filter 
seems to run perfectly:

--8<---------------cut here---------------start------------->8---
λ grep escpr-wrapper -a /var/log/cups/error_log 
D [03/Dec/2021:00:28:45 +0100] [Job 46] epson-escpr-wrapper 
(application/vnd.cups-raster to printer/test, cost 0)
d [03/Dec/2021:00:28:45 +0100] test: File 
\"/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper\" 
permissions OK (040555/uid=0/gid=0).
d [03/Dec/2021:00:28:45 +0100] cupsdStartProcess: Preparing to 
start 
"/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper", 
arguments:
d [03/Dec/2021:00:28:45 +0100] cupsdStartProcess: argv[8] = 
"/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper"
d [03/Dec/2021:00:28:45 +0100] 
cupsdStartProcess(command="/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrapper", 
argv=0x7fffc0e0f148, envp=0x7fffc0e0fad8, infd=25, outfd=28, 
errfd=20, backfd=21, sidefd=23, root=0, profile=(nil), 
job=0x64654c5bf1b0(46), pid=0x64654c5bf2d0) = 32624
I [03/Dec/2021:00:28:45 +0100] [Job 46] Started filter 
/gnu/store/bmb3hz0a4k5a51bb5w7lxlc766d1hcv3-cups-server-bin/lib/cups/filter/epson-escpr-wrappe 
(PID 32624)
D [03/Dec/2021:00:28:45 +0100] [Job 46] pdftopdf: Last filter 
determined by the PPD: epson-escpr-wrapper; FINAL_CONTENT_TYPE: 
application/vnd.cups-raster => pdftopdf will not log pages in 
page_log.
--8<---------------cut here---------------end--------------->8---

So we'll need more info.  Especially your printer model (I chose 
one at random :-) and similar debug log.

Kind regards,

T G-R