i haven problem with "gen_server:handle_common_reply/8 (gen_server.erl, line 751)"

[SIMDI SMART]

root@buscandocasa:/emqx/log# cat run_erl.log
run_erl [3963] Sat May 16 03:25:23 2020
Args before exec of shell:
run_erl [3963] Sat May 16 03:25:23 2020
argv[0] = sh
run_erl [3963] Sat May 16 03:25:23 2020
argv[1] = -c
run_erl [3963] Sat May 16 03:25:23 2020
argv[2] = exec "/emqx/bin/emqx" "console"



//------ cat erlang.log.4
2020-05-17 01:35:13.622 [error] Connection Id 58657 closing with reason: tcp_closed

2020-05-17 01:35:13.622 [error] ** Generic server <0.20490.2> terminating
** Last message in was {tcp_closed,#Port<0.61099>}
** When Server state == {state,[5,7,30],
                               undefined,undefined,gen_tcp,undefined,
                               "127.0.0.1",3306,"admin_login","qE4XhqDUKr",
                               <<103,35,80,4,31,72,39,42,23,81,94,102,48,66,8,
                                 61,49,46,100,1,0>>,
                               true,60000,infinity,60000,0,2,0,0,[],
                               #Ref<0.2307106490.2947547138.259977>,
                               {dict,0,16,16,8,80,48,
                                     {[],[],[],[],[],[],[],[],[],[],[],[],[],
                                      [],[],[]},
                                     {{[],[],[],[],[],[],[],[],[],[],[],[],[],
                                       [],[],[]}}},
                               empty,false}
** Reason for termination ==
** tcp_closed


//---------cat emqx.log


2020-05-17 01:37:03.708 [error] Connection Id 58735 closing with reason: tcp_closed

2020-05-17 01:37:03.708 [error] ** Generic server <0.20607.2> terminating
** Last message in was {tcp_closed,#Port<0.61185>}
** When Server state == {state,[5,7,30],
                               undefined,undefined,gen_tcp,undefined,
                               "127.0.0.1",3306,"admin_login","qE4XhqDUKr",
                               <<84,26,64,3,32,87,18,78,55,29,61,16,66,112,119,
                                 9,53,75,76,12,0>>,
                               true,60000,infinity,60000,0,2,0,0,[],
                               #Ref<0.2307106490.2947809281.246016>,
                               {dict,0,16,16,8,80,48,
                                     {[],[],[],[],[],[],[],[],[],[],[],[],[],
                                      [],[],[]},
                                     {{[],[],[],[],[],[],[],[],[],[],[],[],[],
                                       [],[],[]}}},
                               empty,false}
** Reason for termination ==
** tcp_closed

2020-05-17 01:37:03.708 [error]   crasher:
    initial call: mysql_conn:init/1
    pid: <0.20607.2>
    registered_name: []
    exception exit: tcp_closed
      in function  gen_server:handle_common_reply/8 (gen_server.erl, line 751)
    ancestors: [<0.14260.0>,<0.14245.0>,<0.14243.0>,emqx_auth_mysql_sup,
                  <0.14241.0>]
    message_queue_len: 0
    messages: []
    links: [<0.14260.0>]
    dictionary: []
    trap_exit: true
    status: running
    heap_size: 2586
    stack_size: 27
    reductions: 20079
  neighbours:

2020-05-17 01:37:03.713 [error] Connection Id 58736 closing with reason: tcp_closed

2020-05-17 01:37:03.713 [error] ** Generic server <0.20608.2> terminating
** Last message in was {tcp_closed,#Port<0.61186>}
** When Server state == {state,[5,7,30],
                               undefined,undefined,gen_tcp,undefined,
                               "127.0.0.1",3306,"admin_login","qE4XhqDUKr",
                               <<67,8,59,42,93,2,34,68,13,98,50,108,52,94,61,
                                 10,70,38,59,44,0>>,
                               true,60000,infinity,60000,0,2,0,0,[],
                               #Ref<0.2307106490.2947547138.261783>,
                               {dict,0,16,16,8,80,48,
                                     {[],[],[],[],[],[],[],[],[],[],[],[],[],
                                      [],[],[]},
                                     {{[],[],[],[],[],[],[],[],[],[],[],[],[],
                                       [],[],[]}}},
                               empty,false}
** Reason for termination ==
** tcp_closed

  neighbours:
2020-05-17 01:37:03.739 [error] Connection Id 58737 closing with reason: tcp_closed
2020-05-17 01:37:03.739 [error] ** Generic server <0.20609.2> terminating
** Last message in was {tcp_closed,#Port<0.61187>}
** When Server state == {state,[5,7,30],
                               undefined,undefined,gen_tcp,undefined,
                               "127.0.0.1",3306,"admin_login","qE4XhqDUKr",
                               <<46,91,85,95,61,73,42,46,15,53,98,4,98,122,74,
                                 26,61,59,8,70,0>>,
                               true,60000,infinity,60000,0,2,0,0,[],
                               #Ref<0.2307106490.2947547138.261788>,
                               {dict,0,16,16,8,80,48,
                                     {[],[],[],[],[],[],[],[],[],[],[],[],[],
                                      [],[],[]},
                                     {{[],[],[],[],[],[],[],[],[],[],[],[],[],
                                       [],[],[]}}},
                               empty,false}
** Reason for termination ==
** tcp_closed
2020-05-17 01:37:03.740 [error]   crasher:
    initial call: mysql_conn:init/1
    pid: <0.20609.2>
    registered_name: []
    exception exit: tcp_closed
      in function  gen_server:handle_common_reply/8 (gen_server.erl, line 751)
    ancestors: [<0.14246.0>,<0.14245.0>,<0.14243.0>,emqx_auth_mysql_sup,
                  <0.14241.0>]
    message_queue_len: 0
    messages: []
    links: [<0.14246.0>]
    dictionary: []
    trap_exit: true
    status: running
    heap_size: 2586
    stack_size: 27
    reductions: 20428

  neighbours:

this problem

O.S Ubuntu 18.04.lts

VPS google cloud

EMQX v4.0.4