Am I doing something wrong in gswin64c sDEVICE=pdfwrite? - pdf

Question

I've been using Ghostscript in the command line with
gswin64c sDEVICE=pdfwrite -o out.pdf in.pdf
for a long time now with great success. Ghostscript's location is added to the Path variable setting in Windows 10. And today all of a sudden it stopped to work giving the following error message:
GPL Ghostscript 9.55.0 (2021-09-27)
Copyright (C) 2021 Artifex Software, Inc. All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
Error: /undefinedfilename in (sDEVICE=pdfwrite)
Operand stack:
Execution stack:
%interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push
Dictionary stack:
--dict:762/1123(ro)(G)-- --dict:0/20(G)-- --dict:75/200(L)--
Current allocation mode is local
Last OS error: No such file or directory
GPL Ghostscript 9.55.0: Unrecoverable error, exit code 1
What I've tried so far
update Ghostscript from 9.54 to 9.55.0
different input file
rename input file
different folder containing the input file
copying the input file to the \gs9.55.0\bin\ folder
running the command line with admin privs
running windows logged in as admin
All to no success and always giving me the same error message. All the files tried are being displayed correctly in any pdf viewer.
What am I doing wrong here? And why suddendly?

Answer 1

Easily done but read the error undefinedfilename in (sDEVICE=pdfwrite)
Whilst not very clear, it thinks you are asking for that file to be processed.
However you should have just like for the -o output file switch added the switch - signal.
Then if there is no IN file the message changes
gswin64c -sDEVICE=pdfwrite -o out.pdf in.pdf
GPL Ghostscript 9.55.0 (2021-09-27)
Copyright (C) 2021 Artifex Software, Inc. All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
Error: /undefinedfilename in (in.pdf)
Operand stack:
Execution stack:
%interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push
Dictionary stack:
--dict:764/1123(ro)(G)-- --dict:0/20(G)-- --dict:75/200(L)--
Current allocation mode is local
Last OS error: No such file or directory
GPL Ghostscript 9.55.0: Unrecoverable error, exit code 1
Just a side note that it can sometimes reduce later issues if you get into the habit of using
gswin64c -sDEVICE=pdfwrite -o"out.pdf" -f"in.pdf"