'No pinentry' error (--pinentry-mode loopback with --delete-secret-and-public-key)

[Carola Grunwald]

Hello,

on Wed,  4 May 2016 22:55:34 +0000 (UTC), I wrote:

>I need help with GnuPG 2.1.12 migrating an encryption tool from 1.4.20.
>
>I'm trying to run the --delete-secret-and-public-key command with the
>passphrase entered through stdin, which doesn't get activated ('delete
>key failed: No pinentry').  With --export-secret-keys I was successful
>this way (also added below).  Or can I use --passphrase somehow?

Nobody here with an idea how to solve my problem, to tell me whether a
GnuPG bug prevents success or if it's worth to keep on trying?  I once
thought '--pinentry-mode loopback' is kinda compatibility mode to
simplify transition from 1.4 and allow embedded usage.  I'm stuck.

Caro