ORA-12516: TNS:listener could not find available handler

after the increasing the Number processes in the Oracle database, it solved the problem.

But Before this , i am gonna show you some steps to check the process via OS and Database LETS BEGIN :

  • check if the number of connections reaches the database’s  process parameter using following Unix command:
ps -ef | grep oracleSID | grep -v grep | wc -l
or
ps aux | grep oracleSID | grep -v grep | wc -l
  •  check if the number of connections reaches the database’s  process parameter using following Database Command :
SQL> show parameter processes

NAME TYPE VALUE
------------------ ----------- -------
processes integer 150

SQL> select count(*) from v$process;

COUNT(*)
----------
149
SQL> show parameter sessions

NAME TYPE VALUE
------------------ ----------- -------
Session integer 150

SQL> select count(*) from v$session;

COUNT(*)
----------
149

Now We need To Increase the Both Parameter By :

SQL> alter system set processes=300 scope=spfile;

System altered.
 
SQL> alter system set Session=300 scope=spfile;

System altered.

If this Solution Not Work For you , Try this One :

SQL> alter system set local_listener=
“(ADDRESS=(PROTOCOL=tcp)(HOST=10.122.28.12)(PORT=1521))” sid=’ORCL1′;

System altered.

SQL> show parameter local

NAME                                 TYPE        VALUE
———————————— ———– ——————————
local_listener                       string      (ADDRESS=(PROTOCOL=tcp)(HOST=1
                                                 0.122.28.12)(PORT=1521))

Thank you 

Osama Mustafa