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Oracle Database Error Solutions & DBA Knowledge Base

Welcome to Oracle Database Error Solutions, a professional technical knowledge base dedicated to helping Oracle Database Administrators, Oracle E-Business Suite administrators, developers, and IT professionals troubleshoot Oracle Database and Oracle Linux issues with confidence.

This website provides practical, real-world troubleshooting guides based on hands-on Oracle administration experience. You'll find detailed solutions for Oracle Database errors, RMAN backup and recovery, Data Guard, ASM, RAC, Oracle Linux administration, Oracle E-Business Suite (EBS), cloning, performance tuning, patching, installation, and day-to-day DBA tasks.

Whether you're resolving ORA-27101, ORA-28040, ORA-01555, ORA-12154, ORA-01017, or other Oracle errors, our step-by-step articles are designed to save you time and help you solve problems efficiently.

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ORA-00257: Archiver Error. Connect AS SYSDBA Only Until Resolved – Complete Oracle DBA Troubleshooting Guide

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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...
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ORA-07445: Exception Encountered – Core Dump [Complete Oracle DBA Troubleshooting Guide]

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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...
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ORA-12560: TNS Protocol Adapter Error – Complete Oracle DBA Troubleshooting Guide

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ORA-12560: TNS Protocol Adapter Error – Complete Oracle DBA Troubleshooting Guide Published: July 2026 Last Updated: July 2026 Reading Time: 17 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 The ORA-12560: TNS: Protocol Adapter Error is one of the most frequently encountered Oracle connectivity errors. Unlike errors such as ORA-12154 or ORA-12514 , ORA-12560 generally indicates that the Oracle client cannot establish communication with the Oracle instance because the required Oracle environment, services, or network components are unavailable or incorrectly configured. This error commonly occurs when attempting to connect locally using SQL*Plus, RMAN, Oracle Enterprise Manager, SQL Developer, or other Oracle client applications. It can also appear in scripts, scheduled jobs, Oracle E-Business Suite environments, and backup or recovery operations. ...
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ORA-12545: Connect Failed Because Target Host or Object Does Not Exist – Complete Oracle DBA Troubleshooting Guide

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ORA-12545: Connect Failed Because Target Host or Object Does Not Exist – Complete Oracle DBA Troubleshooting Guide Published: July 2026 Last Updated: July 2026 Reading Time: 16 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c, 23ai, Oracle RAC, Oracle Data Guard, Oracle Cloud Infrastructure (OCI), Oracle Net Services The ORA-12545: Connect failed because target host or object does not exist error is one of the most common Oracle Net Services connectivity problems encountered by Oracle Database Administrators, system administrators, developers, and application teams. Unlike errors such as ORA-12541 , where the Oracle Listener is unavailable, or ORA-12514 , where the listener cannot locate the requested database service, ORA-12545 occurs much earlier in the connection process. The Oracle client cannot locate or communicate with the specified host because the hostname, IP address, DNS resolution, or network routing is incorrect or unavailable. ...
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