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ORA-12541: TNS: No Listener – Complete Step-by-Step Troubleshooting Guide

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ORA-12541: TNS: No Listener – Complete Step-by-Step Troubleshooting Guide Published: April 2026 Last Updated: July 2026 Reading Time: 14–16 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c, 23ai, Oracle RAC, Oracle Grid Infrastructure, Oracle Instant Client, Oracle E-Business Suite, Oracle Cloud Infrastructure (OCI) The ORA-12541: TNS: No Listener error is one of the most common Oracle Net Services connectivity problems encountered by database administrators, developers, and application support teams. It occurs when an Oracle client attempts to connect to a database, but no Oracle Listener is available to accept the incoming connection. Although the error message suggests that the listener is not running, the underlying cause can also be an incorrect hostname, wrong port number, firewall restrictions, listener configuration errors, Oracle Net misconfiguration, or service registration problems. This comprehensive guide explains how Oracle Listener...
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