I find that on Ubuntu 18.04 LTS my emacs 24.5.1 crashes when I copy-and-paste the Unicode symbol "⛔" (no entry) or when I open a file with that character.
I have not encountered another Unicode symbol that crashes emacs (but I haven't tried a broad range). Furthermore, neither vi nor gedit crashes with that character. Firefox also handles the character correctly.
The error message I get reads:
X protocol error: BadLength (poly request too large or internal Xlib length error) on protocol request 139
When compiled with GTK, Emacs cannot recover from X disconnects.
This is a GTK bug: https://bugzilla.gnome.org/show_bug.cgi?id=85715
For details, see etc/PROBLEMS.
(emacs:21722): GLib-WARNING **: 23:00:15.207: g_main_context_prepare() called recursively from within a source's check() or prepare() member.
(emacs:21762): GLib-WARNING **: 23:04:25.943: g_main_context_check() called recursively from within a source's check() or prepare() member.
Fatal error 6: Aborted
Backtrace:
emacs[0x501a83]
emacs[0x4e803e]
emacs[0x501ac3]
emacs[0x4bc7df]
emacs[0x4be8ac]
emacs[0x4be90b]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XError+0x11a)[0x7f07d410a8ba]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3d7eb)[0x7f07d41077eb]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3d895)[0x7f07d4107895]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XEventsQueued+0x55)[0x7f07d41081c5]
/usr/lib/x86_64-linux-gnu/libX11.so.6(XFlush+0x1a)[0x7f07d40e974a]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x5d10e)[0x7f07d412710e]
/usr/lib/x86_64-linux-gnu/libX11.so.6(XDestroyIC+0x12)[0x7f07d4115492]
emacs[0x4cd29c]
emacs[0x4c5f9c]
emacs[0x4c648b]
emacs[0x42583d]
emacs[0x4bc7a0]
emacs[0x4be8ac]
emacs[0x4be90b]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XError+0x11a)[0x7f07d410a8ba]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3d7eb)[0x7f07d41077eb]
/usr/lib/x86_64-linux-gnu/libX11.so.6(+0x3d895)[0x7f07d4107895]
/usr/lib/x86_64-linux-gnu/libX11.so.6(_XEventsQueued+0x55)[0x7f07d41081c5]
/usr/lib/x86_64-linux-gnu/libX11.so.6(XPending+0x5d)[0x7f07d40f9d3d]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x6808e)[0x7f07d592408e]
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_prepare+0x1c8)[0x7f07d4870998]
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x4c36b)[0x7f07d487136b]
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_pending+0x27)[0x7f07d48714f7]
/usr/lib/x86_64-linux-gnu/libgtk-3.so.0(gtk_events_pending+0xd)[0x7f07d5de13fd]
emacs[0x4bc917]
emacs[0x4eeee9]
emacs[0x4f0565]
emacs[0x5bda65]
emacs[0x571b1c]
emacs[0x5bfe63]
emacs[0x5c0397]
emacs[0x5c0d23]
emacs[0x44106f]
emacs[0x4465f0]
emacs[0x44ab0a]
...
Aborted (core dumped)
Is this a bug that needs to be reported somewhere? Is there a workaround? I see there is a discussion at https://gitlab.gnome.org/GNOME/gtk/issues/221
GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.18.9) of 2017-09-20 on lcy01-07, modified by Debian", and pasting from your title, it works, and gives meChar: ⛔ (9940, #o23324, #x26d4, file ...). Your problem may not be ⛔.