When i tried to connect to database, i got the ORA-00020: maximum number of processes (%s) exceeded error. Even from sysdba I was not able to connect.

Solution:

1. connect to database with prelim option and shutdown abort.

$ sqlplus -prelim
SQL> shutdown abort.

exit

2. change the processes parameter to a higher value in the init.ora file.

3. SQL> STARTUP

You should be able to connect now.