On Tue, Nov 30, 2021 at 3:20 PM Marco Wahl <marcowahlsoft@gmail.com> wrote:

>
>
>     diff --git a/lisp/org.el b/lisp/org.el
>     index 1a1375461..fdeec0d67 100644
>     --- a/lisp/org.el
>     +++ b/lisp/org.el
>     @@ -19695,7 +19695,8 @@ non-nil."
>        (save-excursion (forward-char -1) (delete-horizontal-space))
>        (delete-horizontal-space)
>        (indent-to-left-margin)
>     -  (insert-before-markers-and-inherit fill-prefix))
>     +  (when fill-prefix
>     +    (insert-before-markers-and-inherit fill-prefix)))
>
> I don't have anything better.  I think this is a good patch.  It makes
> M-j work again.
>
> Possible refinements and improvements can follow.
>
> +1 for applying of your patch.
>

I am able to reproduce that M-j issue (using Emacs version: GNU Emacs
28.0.60 (build 9, x86_64-pc-linux-gnu, GTK+ Version 3.22.30, cairo version
1.15.12)
 of 2021-11-29, built using commit
c4daff9cf844ec85930bdcd2064787c92c260861, and Org mode version 9.5
(release_9.5-292-g5e35de)).

And this patch fixes that for me as well.

+1 for applying this patch.

=====

Before this patch, M-j gave this backtrace with debug enabled:

Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
  insert-before-markers-and-inherit(nil)
  org-comment-line-break-function(nil)
  default-indent-new-line(nil t)
  funcall-interactively(default-indent-new-line nil t)
  call-interactively(default-indent-new-line nil nil)
  command-execute(default-indent-new-line)


Output of C-h k M-j:

M-j runs the command default-indent-new-line (found in global-map),
which is an interactive compiled Lisp function in ‘simple.el’.

It is bound to C-M-j, M-j.

(default-indent-new-line &optional SOFT FORCE)

Break line at point and indent.
If a comment syntax is defined, call ‘comment-line-break-function’.

The inserted newline is marked hard if variable ‘use-hard-newlines’ is true,
unless optional argument SOFT is non-nil.