TNS:no appropriate service handler found

Error Message:

Caused by: java.sql.SQLException: Listener refused the connection with the following error:

ORA-12519, TNS:no appropriate service handler found

The Connection descriptor used by the client was:

localhost:1521:xe

Cause:

This error is generally caused by the value of allowed processes or sessiones is too small. 

Solution:

Excecute the following command in SQLPLUS to change the parameters of Oracle then restart the oracle service.

alter system set processes=500 scope=spfile sid='*';
alter system set sessions=555 scope=spfile sid='*';
alter system set transactions=610 scope=spfile sid='*';