Hi, I have a problem creating a dump with SQL Developer, the PL/SQL generated is:

set scan off
set serveroutput on
set escape off
whenever sqlerror exit 
DECLARE
    h1 number;
    s varchar2(1000):=NULL;
    errorvarchar varchar2(100):= 'ERROR';
    tryGetStatus number := 0;
    success_with_info EXCEPTION;
    PRAGMA EXCEPTION_INIT(success_with_info, -31627);
begin
    h1 := dbms_datapump.open (operation => 'EXPORT', job_mode => 'FULL', job_name => 'EXP_SD_50-16_18_31', version => 'COMPATIBLE'); 
    tryGetStatus := 1;
    dbms_datapump.set_parallel(handle => h1, degree => 1); 
    dbms_datapump.add_file(handle => h1, filename => 'EXPDAT-'||to_char(sysdate,'hh24_mi_ss')||'.LOG', directory => 'DATA_PUMP_DIR', filetype => 3); 
    dbms_datapump.set_parameter(handle => h1, name => 'KEEP_MASTER', value => 1); 
    dbms_datapump.add_file(handle => h1, filename => 'EXPDAT%U-'||to_char(sysdate,'hh24_mi_ss')||'.DMP', directory => 'DATA_PUMP_DIR', filesize => '500M',  filetype => 1); 
    dbms_datapump.set_parameter(handle => h1, name => 'INCLUDE_METADATA', value => 1); 
    dbms_datapump.set_parameter(handle => h1, name => 'DATA_ACCESS_METHOD', value => 'AUTOMATIC'); 
    dbms_datapump.set_parameter(handle => h1, name => 'ESTIMATE', value => 'BLOCKS'); 
    dbms_datapump.start_job(handle => h1, skip_current => 0, abort_step => 0); 
    dbms_datapump.detach(handle => h1); 
    errorvarchar := 'NO_ERROR'; 
EXCEPTION
    WHEN OTHERS THEN
    BEGIN 
        IF ((errorvarchar = 'ERROR')AND(tryGetStatus=1)) THEN 
            DBMS_DATAPUMP.DETACH(h1);
        END IF;
    EXCEPTION 
    WHEN OTHERS THEN 
        NULL;
    END;
    RAISE;
END;
/

The error Received is:

ORA-39006: internal error
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 79
ORA-06512: at "SYS.DBMS_DATAPUMP", line 3507
ORA-06512: at "SYS.DBMS_DATAPUMP", line 5296
ORA-06512: at line 9

Can you help me? Thank you very much.