org-crypt: GPG error: "no usable configuration"

[hymie! <hymie@lactose.homelinux.net>]

Greetings.

I'm running Orgmode 9.0.3 under emacs 25.1.2 on Microsoft Windows 7.

I think this is really an emacs issue and not an orgmode issue; but
other than orgmode, I don't use emacs, and I don't know where else to
turn.

For a year or so, I've been using org-crypt like this:

(setq exec-path '("C:\\Program Files (x86)\\GNU\\GnuPG"))
(require 'org-crypt)
(org-crypt-use-before-save-magic)
(setq org-tags-exclude-from-inheritance (quote ("crypt")))
(setq org-crypt-key "65B20F70")
(global-set-key "\C-cd" 'org-decrypt-entry)
(global-set-key "\C-ce" 'org-encrypt-entry)

...and it's worked fine, until I recently updated from emacs 24.5 to 25.1
and orgmode from 8.3.5 to 9.0.3 .

Now I get this error:
GPG error: "no usable configuration", OpenPGP

Apparently, it might be related to this bug

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=24229

but the eventual work-around:
>
>  Setting this variable directly does not have any effect;
>  instead use \\[customize] or <some setter function>.
>
>IMO that's all that's needed here too.

makes no sense to me at all.

Can somebody help me get GPG working again?

--hymie!