The failure is observed using Gnome, but thunderbird works fine in LXQt, presumably because LXQt does not use gtk3.
I waited until the fix for #1127558 migrated to my box hoping it would fix it, but it did not. The fix for #1127558 fixed a crash in LibreOffice, and I hoped that fix would fix my thunderbird, but it did not. Here are the error messages I am getting when launching thunderbird on Gnome/Wayland on up-to-date unstable: test@debian:~$ thunderbird ... (some warnings that don't cause crash or failure to launch thunderbird) WARNING: Glycin running without sandbox. [Parent 6011, Main Thread] WARNING: can't init metadata tree /home/test/.local/share/gvfs-metadata/root: open: Permission denied: 'glib warning', file toolkit/xre/nsSigHandlers.cpp:201 (thunderbird:6011): GVFS-WARNING **: 22:21:25.319: can't init metadata tree /home/test/.local/share/gvfs-metadata/root: open: Permission denied [Parent 6011, Main Thread] WARNING: Could not load a pixbuf from icon theme. This may indicate that pixbuf loaders or the mime database could not be found.: 'glib warning', file toolkit/xre/nsSigHandlers.cpp:201 (thunderbird:6011): Gtk-WARNING **: 22:21:25.319: Could not load a pixbuf from icon theme. This may indicate that pixbuf loaders or the mime database could not be found. WARNING: Glycin running without sandbox. [Parent 6011, Main Thread] WARNING: can't init metadata tree /home/test/.local/share/gvfs-metadata/root: open: Permission denied: 'glib warning', file toolkit/xre/nsSigHandlers.cpp:201 (thunderbird:6011): GVFS-WARNING **: 22:21:25.342: can't init metadata tree /home/test/.local/share/gvfs-metadata/root: open: Permission denied ** Gtk:ERROR:../../../gtk/gtkiconhelper.c:495:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /usr/share/icons/Adwaita/scalable/status/image-missing.svg: Could not spawn `env -i XDG_RUNTIME_DIR="/run/user/1000" "/usr/libexec/glycin-loaders/2+/glycin-svg" "--dbus-fd" "49"`: Permission denied (os error 13) (gdk-pixbuf-error-quark, 0) Bail out! Gtk:ERROR:../../../gtk/gtkiconhelper.c:495:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /usr/share/icons/Adwaita/scalable/status/image-missing.svg: Could not spawn `env -i XDG_RUNTIME_DIR="/run/user/1000" "/usr/libexec/glycin-loaders/2+/glycin-svg" "--dbus-fd" "49"`: Permission denied (os error 13) (gdk-pixbuf-error-quark, 0) Redirecting call to abort() to mozalloc_abort ExceptionHandler::GenerateDump attempting to generate:/home/test/.thunderbird/<redacted>/minidumps/577802fb-25fb-4fb6-f847-2957184bc122.dmp ExceptionHandler::GenerateDump cloned child 6121 ExceptionHandler::WaitForContinueSignal waiting for continue signal... ExceptionHandler::SendContinueSignalToChild sent continue signal to child ExceptionHandler::GenerateDump minidump generation succeeded test@debian:~$ Some possibly relevant information about packages installed: test@debian:~$ dpkg-query -l thunderbird ┌── Desired=Unknown/Install/Remove/Purge/Hold │┌─ Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend ││┌ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) │││ Name Version Architecture Description ├┼┼─══════════════─═════════════════─════════════─══════════════════════════════════════════════════════════════════ ii thunderbird 1:140.7.1esr-1+b1 amd64 mail/news client with RSS, chat and integrated spam filter support test@debian:~$ These I think are the packages causing thunderbird to fail to load: test@debian:~$ dpkg-query -l libgdk-pixbuf* ┌── Desired=Unknown/Install/Remove/Purge/Hold │┌─ Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend ││┌ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) │││ Name Version Architecture Description ├┼┼─═══════════════════════════─═════════════─════════════─══════════════════════════════════════ ii libgdk-pixbuf-2.0-0:amd64 2.44.5+dfsg-3 amd64 GDK Pixbuf library ii libgdk-pixbuf-2.0-dev:amd64 2.44.5+dfsg-3 amd64 GDK Pixbuf library (development files) ii libgdk-pixbuf2.0-bin 2.44.5+dfsg-3 amd64 GDK Pixbuf library (thumbnailer) ii libgdk-pixbuf2.0-common 2.44.5+dfsg-3 all GDK Pixbuf library - data files test@debian:~$ This shows thunderbird is still not working even after the fix for LibreOffice (#1127558) was installed on my system: test@debian:~$ dpkg-query -l *glycin* ┌── Desired=Unknown/Install/Remove/Purge/Hold │┌─ Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend ││┌ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) │││ Name Version Architecture Description ├┼┼─═════════════════════─════════════─════════════─═════════════════════════════════ ii glycin-loaders 2.0.7+ds-5 amd64 sandboxed image loaders for GNOME ii glycin-thumbnailers 2.0.7+ds-5 amd64 sandboxed image loaders for GNOME ii libglycin-2-0:amd64 2.0.7+ds-5 amd64 sandboxed image loaders for GNOME ii libglycin-2-dev:amd64 2.0.7+ds-5 amd64 sandboxed image loaders for GNOME test@debian:~$ Other information about the testing environment: I am testing in a virtual machine without hardware acceleration using the bochs-drm graphics driver. I am using Xen as the Hypervisor and qemu, I can check if bug also exists using KVM hypervisor instead if this cannot be reproduced on bare metal or if it is inconvenient for you to try to reproduce this in a Xen HVM sid guest. Thunderbird was working fine in sid before the gdk-pixbuf+glycin transition migrated to my box in this unstable/sid Xen HVM guest.
