The backtrace is as follows:
#0 0x00007fd23dbe35c0 stonith_send_notification (libstonithd.so.26 + 0xa5c0) #1 0x00007fd23d7bb810 g_list_foreach (libglib-2.0.so.0 + 0x56810) #2 0x00007fd23dbdeead foreach_notify_entry (libstonithd.so.26 + 0x5ead) #3 0x00007fd23dbdefd1 stonith_connection_destroy (libstonithd.so.26 + 0x5fd1) #4 0x00007fd23db90c12 mainloop_gio_destroy (libcrmcommon.so.34 + 0x32c12) #5 0x00007fd23d7bb4b5 g_source_callback_unref (libglib-2.0.so.0 + 0x564b5) #6 0x00007fd23d7bf9a4 g_source_destroy_internal (libglib-2.0.so.0 + 0x5a9a4) #7 0x00007fd23d7c0f79 g_main_context_dispatch_unlocked.lto_priv.0 (libglib-2.0.so.0 + 0x5bf79) #8 0x00007fd23d81bdd8 g_main_context_iterate_unlocked.isra.0 (libglib-2.0.so.0 + 0xb6dd8) #9 0x00007fd23d7c2447 g_main_loop_run (libglib-2.0.so.0 + 0x5d447) #10 0x000055c909b97a96 main (crm_mon + 0x5a96) #11 0x00007fd23d8d614a __libc_start_call_main (libc.so.6 + 0x2814a) #12 0x00007fd23d8d620b __libc_start_main@@GLIBC_2.34 (libc.so.6 + 0x2820b) #13 0x000055c909b97ff5 _start (crm_mon + 0x5ff5)
This is consistently reproducible using the current main branch. I haven't established a known good version yet, but I don't believe this has always happened.