Oracle Database Error Solutions & DBA Guide

ORA-00060: Deadlock Detected While Waiting for Resource – Complete Oracle DBA Troubleshooting Guide The ORA-00060: deadlock detected while waiting for resource error is one of the most important Oracle Database concurrency errors encountered in production environments. It occurs when two or more database sessions become trapped in a circular locking dependency, where each session is waiting for a resource held by another session. Because none of the sessions can proceed, Oracle automatically detects the deadlock and resolves it by terminating one of the conflicting SQL statements. Unlike ordinary blocking situations, where one session simply waits for another to complete, a deadlock creates a circular dependency that cannot resolve itself. Oracle's deadlock detection mechanism identifies the cycle, selects one statement as the victim, rolls back only that statement, and allows the remaining transaction to continue. ORA-00060 is commonly encountered in OLTP applicatio...

ORA-00257: Archiver Error. Connect AS SYSDBA Only Until Resolved – Complete Oracle DBA Troubleshooting Guide The ORA-00257: Archiver Error. Connect AS SYSDBA Only Until Resolved error is one of the most common Oracle Database production errors encountered by Database Administrators (DBAs). This error indicates that Oracle can no longer archive online redo logs because the archive destination has become unavailable or full. As a result, normal database users are prevented from establishing new connections until the archiving issue is resolved. Oracle databases running in ARCHIVELOG mode rely on archived redo logs for media recovery, point-in-time recovery, Oracle Data Guard synchronization, RMAN backups, and disaster recovery. When Oracle cannot archive a redo log, the database eventually stops processing new transactions to protect recoverability. Although ORA-00257 most frequently occurs because the Fast Recovery Area (FRA) is full, it may also be caused by a full fil...

ORA-07445: Exception Encountered – Core Dump [Complete Oracle DBA Troubleshooting Guide] The ORA-07445: Exception Encountered: Core Dump error is one of the most critical internal Oracle Database errors encountered by Database Administrators (DBAs). Unlike SQL syntax errors or configuration issues, ORA-07445 indicates that an Oracle server process has terminated unexpectedly after encountering an operating system exception, such as an invalid memory access, segmentation fault, illegal instruction, or arithmetic exception. When ORA-07445 occurs, Oracle immediately terminates the affected process to protect database integrity and automatically generates extensive diagnostic information, including trace files, incident reports, call stacks, and core dump information. These diagnostics are stored in the Automatic Diagnostic Repository (ADR) and are essential for determining the root cause. Although ORA-07445 is often associated with Oracle software bugs, it can also result f...

ORA-12560: TNS Protocol Adapter Error – Complete Oracle DBA Troubleshooting Guide Published: July 2026 Last Updated: October 2026 Reading Time: 18–22 Minutes Applies To: Oracle Database 10g, 11g, 12c, 18c, 19c, 21c, 23ai, Oracle RAC, Oracle Data Guard, Oracle Client, SQL*Plus, RMAN, Oracle Net Services, Windows, Linux and Unix ORA-12560: TNS: Protocol adapter error is an Oracle connectivity error that indicates a problem establishing the requested Oracle connection through the Oracle communication stack. The exact cause depends heavily on how the connection is being made , the operating system, the Oracle client installation, and whether the connection is local or remote. A particularly important troubleshooting distinction is between a local database connection and a remote Oracle Net connection . For example, a command such as sqlplus / as sysdba uses operating-system authentication and a local Oracle connection mechanism. It does not require the list...