ORA-01000: maximum open cursors exceeded

One session has more cursors open than OPEN_CURSORS allows. This is usually a leak: the application does not close its statements or result sets. Fix the leak first; raising the limit only delays the error.

What ORA-01000 means

OPEN_CURSORS limits how many cursors a single session can hold open at the same time. It is a limit per session, not for the whole database. If an application opens a statement in a loop and never closes it, the count grows until ORA-01000 appears, often hours after the application started.

Common causes of ORA-01000

Application code that does not close statements and result sets, especially on error paths.
PL/SQL explicit cursors or ref cursors left open.
A long-lived pooled connection accumulating leaked cursors.
OPEN_CURSORS set too low for a legitimately complex application.

How to fix ORA-01000

See which session and which SQL hold the cursors: V$OPEN_CURSOR.
Close statements and result sets in a finally block or a try-with-resources construct.
Close explicit and ref cursors in PL/SQL, including in the exception handler.
Raise OPEN_CURSORS only if the count stays stable at a high level instead of growing.

ORA-01000 example

Which sessions hold the most cursors, and for which SQL?

SELECT sid, sql_text, COUNT(*) AS cursors
  FROM v$open_cursor
 GROUP BY sid, sql_text
 ORDER BY cursors DESC
 FETCH FIRST 20 ROWS ONLY;

Only if the load is real:

ALTER SYSTEM SET open_cursors = 1000 SCOPE = BOTH;

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Oracle documentation for ORA-01000. Oracle is a registered trademark of Oracle Corporation. SQLlightspeed is not affiliated with Oracle.