bug#27816: 26.0.50; X protocol error: BadPixmap (invalid Pixmap parameter) on protocol request 55

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 27 Jul 2017 10:38:27 +0300
> From: Jean Louis <bugs@gnu.support>
> Cc: 27816@debbugs.gnu.org
> 
> I am starting Emacs through screen, without X windows. So I started as:
> 
> gdb screen
> 
> then I do:
> 
> breakpoint x_error_quitter
> 
> It asks me for future loaded libraries, I said y.
> 
> Then I "run" and get screen and bash.
> 
> Then I start emacs as 
> 
> emacs --user admin --chdir /home/data1/protected (that is my home dir)

No, I think this is a mistake.  You should first start screen, then
start GDB from that like this:

  gdb emacs

Then when GDB shows its prompt, type

  (gdb) break x_error_quitter
  (gdb) run  --user admin --chdir /home/data1/protected

(The "(gdb)" part is the GDB prompt, you don't need to type it.)
And then continue as you usually would:

> And then I connect to emacs as emacsclient
> 
> and evaluate (x-synchronize t)
> 
> and then if I connect each 4th or 5th time, not clearly known why,
> then I get that bug, and X frame of new emacsclient is not appearing.
> 
> But back in debugger I do not see much, emacs as server is still
> running.

If you start Emacs as above, you should see GDB take control when the
problem happens.  Then type

  (gdb) thread apply all bt

and post here everything it displays.