Sep  2 19:08:34 ./kamailio[3712]: : tm [t_fwd.c:1632]: t_send_branch(): BUG: t_send_branch: retr. already started for 0x41848fa0

Sep  2 19:08:34 ./kamailio[3712]: ERROR: sl [sl_funcs.c:387]: sl_reply_error(): ERROR: sl_reply_error used: Unfortunately error on sending to next hop occurred (477/SL)

At this point the related behavior is that Kamailio received two INFO requests simultaneously. I wonder whether this is the cause.

And maybe it's related to the later crash?

Sep  2 19:08:35 ./kamailio[3713]: CRITICAL: <core> [pass_fd.c:293]: receive_fd(): EOF on 11

Sep  2 19:08:35 ./kamailio[3703]: ALERT: <core> [main.c:784]: handle_sigs(): child process 3704 exited by a signal 11

Sep  2 19:08:35 ./kamailio[3703]: ALERT: <core> [main.c:787]: handle_sigs(): core was generated

Sep  2 19:08:35 ./kamailio[3703]: : <core> [mem/f_malloc.c:586]: fm_free(): BUG: fm_free: bad pointer 0x7239b6c4 (out of memory block!), called from tm: h_table.c: free_cell(157) - aborting