Oracle error
ORA-00020
ORA-00020: maximum number of processes (%s) exceeded
What usually causes it
The instance reached its PROCESSES limit. Every dedicated server connection and background process counts toward it.
What to check first
If you can't log in, sqlplus -prelim / as sysdba attaches without a process slot, which is enough for diagnostics or SHUTDOWN ABORT. Find who is holding connections, then raise PROCESSES in the spfile and restart.
Scripts that help
- Processes and sessions against their limitsCurrent and peak usage of processes, sessions and transactions since startup. A PEAK % near 100 means the next connection storm will hit ORA-00020.
- Session count by user and machineWho is connected, from where, and how many are active. The quickest way to spot a connection pool that has run away.
- Working with the spfileShows which spfile the instance is using, where parameter files live and the order Oracle searches for them, and what SCOPE = MEMORY, SPFILE and BOTH…