Why Oracle 12c TNS Listener Returns ORA-12514 and How to Fix It

The article recounts a troubleshooting session where a 12c Oracle standby database failed to connect via TNS, presenting the ORA-12514 error, analyzing listener and tnsnames configurations, uncovering an outdated 11g ORACLE_HOME, and detailing the steps to switch homes and restart the listener to resolve the issue.

12cORA-12514Oracle

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Why Oracle 12c TNS Listener Returns ORA-12514 and How to Fix It

dbaplus Community

Dec 22, 2015 · Databases

How to Diagnose and Fix Common Oracle Listener Errors

This article details seven common Oracle Listener issues—including intermittent connections, process crashes, ORA-12514, SCAN registration failures, listener hangs, TNS-12535/00505 errors, and TNS-12547 lost-contact—explaining symptoms, root causes, and step-by-step remediation commands for DBA teams.

Error CodesOracleTNS

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How to Diagnose and Fix Common Oracle Listener Errors