Oracle Database Error Solutions & DBA Guide

ORA-03113: End-of-File on Communication Channel – Complete Oracle DBA Troubleshooting Guide Published: May 2026 Last Updated: October 2026 Reading Time: 18–22 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c, Oracle Database 23ai, Oracle RAC, Oracle Data Guard, Oracle Client, SQL*Plus, RMAN, Oracle Net Services and Oracle E-Business Suite The ORA-03113: end-of-file on communication channel error indicates that communication between an Oracle client and the Oracle server process was unexpectedly broken. It is one of the most important Oracle Database communication errors because the message itself usually does not identify the actual root cause. ORA-03113 should therefore be treated as a symptom rather than the underlying failure . The real problem may be an Oracle server-process termination, database instance outage, Oracle internal error, operating-system failure, storage or I/O problem, network interruption, firewall timeout, RAC node failu...

ORA-00054: Resource Busy and Acquire with NOWAIT Specified or Timeout Expired – Complete Oracle DBA Troubleshooting Guide The ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired error is one of the most frequently encountered Oracle Database locking errors. It occurs when a session attempts to acquire a lock on a database object that is already locked by another session, and Oracle cannot obtain the required lock immediately. ORA-00054 commonly occurs during DDL operations such as ALTER TABLE , DROP TABLE , TRUNCATE TABLE , CREATE INDEX , and ALTER INDEX REBUILD . It may also occur during application deployments, Oracle E-Business Suite maintenance, Data Pump operations, schema changes, or any task requiring an exclusive lock while another session is actively using the object. Unlike deadlocks, ORA-00054 does not indicate a circular dependency between sessions. Instead, it simply means that the requested resource is currently unavailable because...

ORA-12514: TNS Listener Does Not Currently Know of Service Requested in Connect Descriptor – Complete Oracle DBA Guide Published: May 2026 Last Updated: July 2026 Reading Time: 15 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c, 23ai, Oracle RAC, Oracle Data Guard, Oracle Net Services, Oracle Cloud Infrastructure (OCI) The ORA-12514: TNS listener does not currently know of service requested in connect descriptor error is one of the most common Oracle Net Services errors encountered by Oracle Database Administrators, developers, and application administrators. This error occurs when a client successfully reaches the Oracle Listener, but the listener cannot find the requested database service. Unlike network connectivity issues where the listener is unavailable, ORA-12514 indicates that communication with the listener has been established; however, the specified SERVICE_NAME has not been registered or recognized. ORA-12514 commonly appears a...