On Wed, 29 Jan 2020 12:48:42 +0100 Michael Heerdegen <michael_heerdegen@web.de> wrote:

> Hello,
>
> since today (master built) when exiting Gnus I get this error:
>
> Debugger entered--Lisp error: (error "Selecting deleted buffer")
>   set-buffer(#<killed buffer>)
[...]
> Could this be due to
>
> | Make sure that all gnus buffers are killed on exit
> | 5ee3c37634f7f8651b2da1f4b611334a2b146928
> | Author:     Sam Steingold <sds@gnu.org>
> | AuthorDate: Fri Jan 10 13:34:59 2020 -0500
>
> ?
>
> AFAICT `my-gnus-clear-system-around-ad' is unrelated, it looks like
>
> (defun my-gnus-clear-system-around-ad (f &rest args)
>               (let ((kill-buffer-query-functions kill-buffer-query-functions))
>                 (remove-hook 'kill-buffer-query-functions 'process-kill-buffer-query-function)
>                 (apply f args)))
>
> The problem rather seems to be that the return value of (gnus-buffers)
> contains killed buffers.

I see this too.  The patch below appears to fix it for me, but I don't
know if it's just a workaround.

Steve Berman