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

Issue:Listener refuses connection with error :ORA-12516: TNS:listener could not find available handler
Root Cause: exceeding number of process by connection ..
Solution:
Checked with number of connection to the database:
SQL> select count(*) from v$session;

  COUNT(*)
----------
       142

Increased process with scope of spfile

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

System altered.

SQL> startup force;

ORACLE instance started.

Total System Global Area 1104814080 bytes

Fixed Size                  1335980 bytes

Variable Size             838864212 bytes

Database Buffers          251658240 bytes

Redo Buffers               12955648 bytes

Database mounted.

Database opened.

SQL>

 Then check connection it will connect to database... from any tool or application..... :)