Unable To Connect To "<service_name_XDB>" Service - ORA-12520: TNS:listener Could Not Find Available Handler
(Doc ID 2152756.1)
Last updated on JANUARY 17, 2025
Applies to:
Oracle Net Services - Version 12.1.0.1 and laterGen 2 Exadata Cloud at Customer - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Exadata Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 21.12 and later
Information in this document applies to any platform.
Symptoms
================== Issue Clarification ==================
When trying to connect to the XDB service, the connection is failing with the error ORA-12520.
The lsnrctl output shows that the XDB services have registered with the listener.
SQL> conn <username>/<password>@<service_name_XDB> <<<ERROR: ORA-12520: TNS:listener could not find available handler for requested type of server
SQL> show parameter dispatchers;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dispatchers string (PROTOCOL=TCP) (SERVICE=<service_name_XDB>)
C:\>lsnrctl services
LSNRCTL for 64-bit Windows: Version 12.1.0.2.0 - Production on 13-JUN-2016 16:26
:07
Copyright (c) 1991, 2014, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=<hostname>)(PORT=1521)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0
LOCAL SERVER
Service "<service_name>.<domain>" has 1 instance(s).
Instance "<instance_name>", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:88862 refused:0 state:ready
LOCAL SERVER
Service "<service_name_XDB>.<domain>" has 1 instance(s).
Instance "<instance_name>", status READY, has 1 handler(s) for this service...
Handler(s):
"D000" established:0 refused:0 current:0 max:1022 state:ready
DISPATCHER
(ADDRESS=(PROTOCOL=tcp)(HOST=<hostname>)(PORT=56033))
The command completed successfully
------------------------------------------------------------------------------------------------
The tnsnames.ora entry shows:
service_name_XDB =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = <hostname>)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED) <===This is incorrect
(SERVICE_NAME = <service_name_XDB>)
)
)
Changes
None.
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |