ERROR: ORA-00020: maximum number of processes (%s) exceeded

Problem:

 ERROR: ORA-00020: maximum number of processes (%s) exceeded

Cause:

 Current session count reached processes parameter threshold.

Solution:

 1) sqlplus -prelim / as sysdba
    to hang analyze..
 2) Kill some (LOCAL=NO) processes and login.

* Prelim is a way to connect to a database through sqlplus when all other connection methods are hanging. Using a sqlplus preliminary connection, you will be able to connect to the database since no session is actually created, but you will have limited access to the SGA. This will help in capturing diagnostic information like hanganalyze and systemstate dumps to aid in problem resolution.

 

How To Connect Using A Sqlplus Preliminary Connection [ID 986640.1]