Ok, thanks. It must be some dependency in one of the packages.

On Sun, Oct 11, 2020, 18:16 Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Gábor <hajovonta@gmail.com>
> > Date: Sun, 11 Oct 2020 17:09:27 +0200
> > Cc: Lars Ingebrigtsen <larsi@gnus.org>, 43888@debbugs.gnu.org
> >
> > I have the with-editor package, but: a) it's up-to-date b) removing it
> from the configuration did not solve the
> > problem, c) running emacsclient from outside of Emacs gives the same
> error. :(
>
> But since with "emacs -Q" it does work, it is still some of your
> customizations that are the prime suspect.
>