[SR-Users] Multiple crashes of Kamailio 4.2.1

Hello, 3 crashes occurred today (we never seen crashes on this server before) during a period of 20 minutes. I had a look to the coredumps. Here is a quick overview of the first entries of "bt full": core.27671 : #0 0x00007f5577048d65 in run_trans_callbacks_internal (cb_lst=0x7f5560abbd50, type=2, trans=0x7f5560abbce0, params=0x7fff3712acb0) at t_hooks.c:286 core.27656 : #0 0x00007f557700a048 in free_cell (dead_cell=0x7f5560abbce0) at h_table.c:175 core.27685 : #0 0x00007f5577048d65 in run_trans_callbacks_internal (cb_lst=0x7f5560abbd50, type=2, trans=0x7f5560abbce0, params=0x7fff3712acb0) at t_hooks.c:286 core.27689 : #0 0x00007f5577048d65 in run_trans_callbacks_internal (cb_lst=0x7f5560abbd50, type=2, trans=0x7f5560abbce0, params=0x7fff3712acb0) at t_hooks.c:286 core.27691 : #0 0x00007f5577048d65 in run_trans_callbacks_internal (cb_lst=0x7f5560abbd50, type=2, trans=0x7f5560abbce0, params=0x7fff3712acb0) at t_hooks.c:286 core.31977 : #0 0x00007f038e66fdee in free_cell (dead_cell=0x7f037811ebe0) at h_table.c:157 core.31994 : #0 0x00007f038e6ab65a in t_forward_nonack (t=0x7f037811ebe0, p_msg=0x7f038fdca438, proxy=0x0, proto=0) at t_fwd.c:1762 core.3700 : #0 0x000000000061697a in fm_insert_free (qm=0x7f19861fa000, frag=0x7f19864d53e8) at mem/f_malloc.c:245 core.3727 : #0 0x00000000006167a4 in fm_extract_free (qm=0x7f19861fa000, frag=0x7f19864f4cc8) at mem/f_malloc.c:208 I don't know how to proceed now. Can you help me to highlight the issue here? Thank you. Regards, Igor.