Altering Max Processes in Oracle

If you are getting Oracle error ORA-00020, it means you've reached the max number of user processes.

To fix this:

sqlplus "/as sysdba"

Show the configuration file:

> show parameter spfile;

Show current max user processes:

> show parameter processes;

Change the max value, and set in the configuration file:

> alter system set processes = 175 scope=spfile;

Shutdown and startup again, using the configuration file:

> shutdown immediate;
> startup;

Verify the max processes has been changed:

> show parameter processes;