My Oracle Support Banner

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

Last updated on SEPTEMBER 04, 2023

Applies to:

Oracle Database - Enterprise Edition - Version and later
Information in this document applies to any platform.


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:


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.