ORA-12519, TNS:no appropriate service handler found

$ sqlplus "sys/password as sysdba"

SQL> alter system set processes=150 scope=spfile;
System altered.

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup
ORACLE instance started.

Total System Global Area  603979776 bytes
Fixed Size                  1260292 bytes
Variable Size             163579132 bytes
Database Buffers          436207616 bytes
Redo Buffers                2932736 bytes
Database mounted.
Database opened.