Oracle: ORA-12519, TNS: no appropriate service handler found

Este error puede tener varias causas, pero en el caso particular me estaba molestando este error al tratar de abrir nuevas conexiones porque aparantemente había excedido la cantidad máxima de procesos y/o sessiones permitidas.

Afortundamente este valor se puede modificar con una simple sentencia SQL(es necesario reiniciar el Oracle):

alter system set processes=150 scope=spfile;

SQL*Plus: Release 10.2.0.1.0 - Production on Thu Jun 27 14:46:58 2013

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Connected to:
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production

SQL> select * from v$resource_limit where resource_name in ('processes','sessions');

RESOURCE_NAME                  CURRENT_UTILIZATION MAX_UTILIZATION
------------------------------ ------------------- ---------------
INITIAL_ALLOCATION
----------------------------------------
LIMIT_VALUE
----------------------------------------
processes                                       38              40
        40
        40

sessions                                        42              49
        49
        49

RESOURCE_NAME                  CURRENT_UTILIZATION MAX_UTILIZATION
------------------------------ ------------------- ---------------
INITIAL_ALLOCATION
----------------------------------------
LIMIT_VALUE
----------------------------------------


SQL> alter system set processes=150 scope=spfile;

System altered.

SQL> exit
Disconnected from Oracle Database 10g Express Edition Release 10.2.0.1.0 - Production
gabo@gabo-Precision-M6600:/usr/lib/oracle/xe/app/oracle/product/10.2.0/server$ sudo /etc/init.d/oracle-xe restart
Shutting down Oracle Database 10g Express Edition Instance.
Stopping Oracle Net Listener.

Starting Oracle Net Listener.
Starting Oracle Database 10g Express Edition Instance.