Troubleshooting Guide - ORA-18: Maximum Number Of Sessions (%S) Exceeded (Doc ID 1307128.1)

Last updated on DECEMBER 06, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 10.2.0.4 and later
Information in this document applies to any platform.
***Checked for relevance on 13-Sep-2016***

Symptoms

You receive the following errors when trying to make new connections:

    ORA-00604: error occurred at recursive SQL level 1
        Cause: An error occurred while processing a recursive SQL statement.
               (a statement applying to internal dictionary tables).
       Action: If the situation described in the next message on the stack can be corrected, do so; otherwise, contact customer support.

    ORA-00018: maximum number of sessions exceeded
        Cause: An operation requested a resource that was unavailable.
               The maximum number of sessions is specified by the initialization parameter SESSIONS.
               When this maximum is reached, no more requests are processed.
       Action: Try the operation again in a few minutes.
               If this message occurs often, shut down Oracle, increase the SESSIONS parameter in the initialization parameter file, and restart Oracle.

NOTE: No new connections are permitted to the database.

However when querying v$resource_limit it shows this is not true.

 
As seen the current number of running sessions is no where near the settings for the sessions parameter yet the following error is still reported:
ORA-18 MAXIMUM NUMBER OF SESSIONS EXCEEDED

Cause

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