Dovecot Deliver core-dump with bt full

(gdb) bt full
#0  0x00007fd083fb6bb9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
        resultvar = 0
        pid = 29807
        selftid = 29807
#1  0x00007fd083fb9fc8 in __GI_abort () at abort.c:89
        save_stage = 2
        act = {__sigaction_handler = {sa_handler = 0x400, sa_sigaction = 0x400}, sa_mask = {__val = {140533577564224, 186, 140533577531472, 512, 140533548337043, 140533577531472, 140533577531472, 512, 140533548329357, 140734102664872, 140533548473618,
              140533577531472, 140734102664776, 140533577568000, 140533548473721, 140533577531472}}, sa_flags = -2076564310, sa_restorer = 0x7fff36327601}
        sigs = {__val = {32, 0 <repeats 15 times>}}
#2  0x00007fd0843a6298 in default_fatal_finish (type=<optimized out>, status=status@entry=0) at failures.c:192
        backtrace = 0x7fd085f7c088 "/usr/lib/dovecot/libdovecot.so.0(+0x5e271) [0x7fd0843a6271] -> /usr/lib/dovecot/libdovecot.so.0(+0x5e34e) [0x7fd0843a634e] -> /usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7fd084361a9e] -> /usr/lib/d"...
#3  0x00007fd0843a634e in i_internal_fatal_handler (ctx=0x7fff36327690, format=<optimized out>, args=<optimized out>) at failures.c:653
        status = 0
#4  0x00007fd084361a9e in i_panic (format=format@entry=0x7fd0843d9d78 "io_add(0x%x) called twice fd=%d, callback=%p -> %p") at failures.c:264
        ctx = {type = LOG_TYPE_PANIC, exit_status = 0, timestamp = 0x0}
        args = {{gp_offset = 40, fp_offset = 48, overflow_arg_area = 0x7fff36327780, reg_save_area = 0x7fff363276c0}}
#5  0x00007fd0843b6533 in ioloop_iolist_add (list=<optimized out>, io=io@entry=0x7fd085f85ad0) at ioloop-iolist.c:26
        i = <optimized out>
        idx = <optimized out>
#6  0x00007fd0843b6cbb in io_loop_handle_add (io=io@entry=0x7fd085f85ad0) at ioloop-epoll.c:98
        ctx = 0x7fd085f84f50
        list = 0x7fd085f85648
        event = {events = 128416, data = {ptr = 0x4000000000, fd = 0, u32 = 0, u64 = 274877906944}}
        op = <optimized out>
        first = <optimized out>
#7  0x00007fd0843b59fb in io_add (fd=fd@entry=7, condition=condition@entry=IO_READ, source_linenum=source_linenum@entry=895, callback=callback@entry=0x7fd084367530 <master_service_listen>, context=context@entry=0x7fd085f85aa0) at ioloop.c:58
        io = 0x7fd085f85ad0
        __FUNCTION__ = "io_add"
#8  0x00007fd084366e49 in master_service_io_listeners_add (service=0x7fd085f84660) at master-service.c:894
        l = 0x7fd085f85aa0
        i = 0
        service = 0x7fd085f84660
#9  0x00007fd084366f90 in master_service_init_finish (service=0x7fd085f84660) at master-service.c:455
        sigint_flags = <optimized out>
        st = {st_dev = 0, st_ino = 140533547922080, st_nlink = 140533558524080, st_mode = 2218020416, st_uid = 32720, st_gid = 2, __pad0 = 0, st_rdev = 0, st_size = 140734102665632, st_blksize = 140533544828091, st_blocks = 140533547934560, st_atim = {
            tv_sec = 140531329925120, tv_nsec = 140533577565792}, st_mtim = {tv_sec = 140533544828168, tv_nsec = 140733193388032}, st_ctim = {tv_sec = 140533558524080, tv_nsec = 140533547945536}, __glibc_reserved = {140533548082632, 0,
            140533550870968}}
#10 0x00007fd084d5a69b in main (argc=5, argv=0x7fd085f84390) at main.c:401
        set_roots = {0x7fd084b2b580 <lda_setting_parser_info>, 0x0}
        ctx = {pool = 0x7fd085f84b10, set = 0x0, session = 0x7fd085f84b30, dup_ctx = 0x0, session_id = 0x0, src_mail = 0x0, src_envelope_sender = 0x0, dest_user = 0x0, dest_addr = 0x0, final_dest_addr = 0x0,
          dest_mailbox_name = 0x7fd085f843f9 "Training.HAM", dest_mail = 0x0, var_expand_table = 0x0, tempfail_error = 0x0, tried_default_save = false, saved_mail = false, save_dest_mail = false, mailbox_full = false, dsn = false}
        service_flags = MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP
        user = 0x7fd085f843dc "sa-training@localhost.com"
        errstr = 0x7fff363d0268 ""
        path = 0x0
        lda_set = <optimized out>
        storage_service = 0x7fff36327ac0
        service_user = 0x0
        service_input = {module = 0x0, service = 0x0, username = 0x7fff36327be8 ">\216\062\066\377\177", session_id = 0x0, local_ip = {family = 1, u = {ip6 = {__in6_u = {__u6_addr8 = '\000' <repeats 15 times>, __u6_addr16 = {0, 0, 0, 0, 0, 0, 0, 0},
                  __u6_addr32 = {0, 0, 0, 0}}}, ip4 = {s_addr = 0}}}, remote_ip = {family = 0, u = {ip6 = {__in6_u = {__u6_addr8 = "\350{26\377\177\000\000\005\000\000\000\000\000\000", __u6_addr16 = {31720, 13874, 32767, 0, 5, 0, 0, 0},
                  __u6_addr32 = {909278184, 32767, 5, 0}}}, ip4 = {s_addr = 909278184}}}, local_port = 909277936, remote_port = 32767, userdb_fields = 0x7fd084d541c8, flags_override_add = (unknown: 0), flags_override_remove = (unknown: 0),
          no_userdb_lookup = 1}
        storage = 0x0
        user_source = 0x7fd084d5b59a ""
        destaddr_source = 0x7fd084d5b59a ""
        process_euid = <optimized out>
        stderr_rejection = false
        ret = <optimized out>
        c = <optimized out>
        error = 909277936
(gdb)