Hi Lars,

Sorry, the attachment is the "dribble-file" from an "emacs -Q" session.  Since it's mentioned in the Emacs manual (section 52.4), I thought it would be useful!  Here's the same recipe in straight text:
1. emacs -Q
2. "C-x d ~/"  open home directory
3. navigate to any subdirectory (eg, ".emacs.d")
4. "i" insert the subdirectory at point
5. "$" hide the subdir
6. "C-x C-q" attempt to put dired buffer into writable mode.  This will fail with message "Buffer is read-only"
7. "$" unhide the subdir
8. "C-x C-q" new attempt to put dired buffer into writable mode.  This works as expected
9. "C-c C-k" exit writable dired mode.

Peter


On Fri, Jul 22, 2022 at 10:56 PM Lars Ingebrigtsen <larsi@gnus.org> wrote:
Peter Mao <peter.mao@gmail.com> writes:

> If any of the subdirs (or even the top dir) is hidden in a dired buffer,
> `wdired-change-to-wdired-mode' fails.  I believe this is happening at `dired--unhide'
> called from `dired-remember-marks'.
>
> Running 'C-x C-q' , with a hidden subdir results in a "Buffer is read-only" message.
> 'C-x C-q' works properly after manually unhiding the subdirs.
>
> Recipe is attached, since my mail client seems to strip out control characters.

I'm not sure what the attachment is supposed to describe, but do you
have a complete, step-by-step recipe to reproduce the problem, starting
from "emacs -Q"?