ORA-24247: network access denied by access control list (ACL) - ERROR

Question

BEGIN
 DBMS_NETWORK_ACL_ADMIN.APPEND_HOST_ACE
 (
 host => '127.0.0.1',
 lower_port => null,
 upper_port => null,
 ace => xs$ace_type(privilege_list => xs$name_list('jdwp'),
 principal_name => 'SYSTEM',
 principal_type => xs_acl.ptype_db)
 );
END;

Getting below error while debugging the function

Connecting to the database SYSTEM.

Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '127.0.0.1', '4000' )
ORA-24247: network access denied by access control list (ACL)
ORA-06512: at "SYS.DBMS_DEBUG_JDWP", line 68
ORA-06512: at line 1
Process exited.
Disconnecting from the database SYSTEM.