I am definitely no newbie and I think I now followed every little advice I could find online, and after 2 days doc-view is still not working :-( (it works fine on my older laptop under windows 10)
On my new laptop (windows 10) I installed emacs 25.2.1 (x86_64-w64-mingw32), I installed 64-bit-Ghostscript, I put the line
(setq doc-view-ghostscript-program "C:\gs\gs9.20\bin")
in my .emacs, I checked the PATH, I copied the dlls zlib1.dll, libtiff-5.dll, libpng16-16.dll, gsdll64.dll in the emacs bin directory.
Yesterday, I installed cygwin64 and it worked partly, but doc-view was breaking from time to time when the document contains images, and I thought it could be a problem, when my ming32-based emacs uses some cygwin programming or dlls. But now, without cygwin, doc-view stopped to work.
I am not really familiar with emacs lisp, but evaluating
t. Opening a pdf-File yield just the pdf source text. Forcing Emacs to enter
Unable to render file. View extraced text instead?
The ghostscript executables are in my PATH.
Any suggestions, how I can debug this problem?