Core was generated by `dovecot/imap'.
Program terminated with signal 6, Aborted.
#0  0x00007fbf87b25475 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt full
#0  0x00007fbf87b25475 in raise () from /lib/x86_64-linux-gnu/libc.so.6
No symbol table info available.
#1  0x00007fbf87b286f0 in abort () from /lib/x86_64-linux-gnu/libc.so.6
No symbol table info available.
#2  0x00007fbf87ef71c9 in default_fatal_finish (type=LOG_TYPE_PANIC, status=0) at failures.c:191
        backtrace = 0x194bf58 "/usr/local/lib/dovecot/libdovecot.so.0(+0x7a1a2) [0x7fbf87ef71a2] -> /usr/local/lib/dovecot/libdovecot.so.0(+0x7b4cd) [0x7fbf87ef84cd] -> /usr/local/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7fbf87ef7"...
#3  0x00007fbf87ef84cd in i_internal_fatal_handler (ctx=0x7fffb895a7b0, format=0x7fbf8828f4c0 "file %s: line %d (%s): assertion failed: (%s)", args=0x7fffb895a798) at failures.c:652
        status = 0
#4  0x00007fbf87ef74a5 in i_panic (format=0x7fbf8828f4c0 "file %s: line %d (%s): assertion failed: (%s)") at failures.c:263
        ctx = {type = LOG_TYPE_PANIC, exit_status = 0, timestamp = 0x0}
        args = {{gp_offset = 40, fp_offset = 48, overflow_arg_area = 0x7fffb895a880, reg_save_area = 0x7fffb895a7c0}}
#5  0x00007fbf8822776e in index_attachment_save_finish (ctx=0x19ed140) at index-attachment.c:231
        attach = 0x1a0d870
        __FUNCTION__ = "index_attachment_save_finish"
#6  0x00007fbf881b3ab0 in dbox_save_end (ctx=0x19ed140) at dbox-save.c:106
        mdata = 0x19ed150
        dbox_output = 0x1a07008
        __FUNCTION__ = "dbox_save_end"
#7  0x00007fbf881aadf7 in mdbox_save_finish_write (_ctx=0x19ed140) at mdbox-save.c:198
        ctx = 0x19ed140
        mail = 0x636c08
#8  0x00007fbf881aaf5d in mdbox_save_finish (ctx=0x19ed140) at mdbox-save.c:228
        ret = 0
#9  0x00007fbf872c505b in quota_save_finish (ctx=0x19ed140) at quota-storage.c:281
        qbox = 0x19e0a50
#10 0x00007fbf882041f7 in mailbox_save_finish (_ctx=0x1971498) at mail-storage.c:2022
        ctx = 0x19ed140
        t = 0x19ebdc0
        keywords = 0x0
        pvt_flags = 0
        copying_via_save = false
        ret = 0
        __FUNCTION__ = "mailbox_save_finish"
#11 0x000000000040d165 in cmd_append_continue_message (cmd=0x1971340) at cmd-append.c:802
        all_written = true
        client = 0x1970760
        ctx = 0x1971438
        ret = 0
#12 0x000000000041a04e in command_exec (cmd=0x1971340) at imap-commands.c:156
        hook = 0x1954da0
        ret = false
#13 0x000000000040b9be in client_input_append (cmd=0x1971340) at cmd-append.c:112
        ctx = 0x1971438
        client = 0x1970760
        reason = 0x7fbf87ef5033 "H\213\005.3'"
        finished = false
        __FUNCTION__ = "client_input_append"
#14 0x00007fbf87f0e58d in io_loop_call_io (io=0x19de2a0) at ioloop.c:387
        ioloop = 0x1953720
        t_id = 2
#15 0x00007fbf87f101ed in io_loop_handler_run (ioloop=0x1953720) at ioloop-epoll.c:215
        ctx = 0x1953aa0
        events = 0x1953b10
        event = 0x1953b10
        list = 0x1971290
        io = 0x19de2a0
        tv = {tv_sec = 59, tv_usec = 999033}
        events_count = 6
        msecs = 60000
        ret = 1
        i = 0
        j = 0
        call = true
        __FUNCTION__ = "io_loop_handler_run"
#16 0x00007fbf87f0e630 in io_loop_run (ioloop=0x1953720) at ioloop.c:406
No locals.
#17 0x00007fbf87ea609e in master_service_run (service=0x19535b0, callback=0x426143 <client_connected>) at master-service.c:560
No locals.
#18 0x000000000042645c in main (argc=1, argv=0x1953390) at main.c:400
        set_roots = {0x42f500, 0x0}
        login_set = {auth_socket_path = 0x194b050  <incomplete sequence \335>, postlogin_socket_path = 0x0, postlogin_timeout_secs = 60, callback = 0x425f07 <login_client_connected>, failure_callback = 0x4260cf <login_client_failed>, request_auth_token = 1}
        service_flags = MASTER_SERVICE_FLAG_KEEP_CONFIG_OPEN
        storage_service_flags = MAIL_STORAGE_SERVICE_FLAG_DISALLOW_ROOT
        username = 0x0
        c = -1