Oracle Database Error Solutions & DBA Guide

ORA-28001: Password Expired in Oracle – Complete Step-by-Step Solution Published: April 2026 Last Updated: July 2026 Reading Time: 12–15 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c, 23ai, Oracle RAC, Oracle Data Guard, Oracle E-Business Suite, Oracle Cloud Infrastructure (OCI) The ORA-28001: the password has expired error occurs when an Oracle database user attempts to log in using an expired password. Oracle automatically enforces password expiration based on the user's assigned profile and security policies to improve database security. Although resetting the password usually resolves the issue, database administrators should also understand why the password expired, how Oracle password profiles work, and whether security policies need to be adjusted for production environments. This comprehensive guide explains the causes of ORA-28001, demonstrates production-tested troubleshooting techniques, and shares best practices for managing Or...

ORA-01652: Unable to Extend Temp Segment by %s in Tablespace TEMP – Complete Oracle DBA Troubleshooting Guide The ORA-01652: unable to extend temp segment error is one of the most common Oracle Database errors encountered in production environments. It occurs when Oracle cannot allocate additional temporary space required to complete an operation such as sorting, hashing, index creation, Data Pump import/export, parallel execution, or large SQL queries. Unlike permanent tablespaces, the TEMP tablespace is used only for temporary work areas created during SQL execution. When sufficient temporary space is unavailable, Oracle terminates the operation and raises ORA-01652 to protect database stability. Although the error appears to indicate a lack of disk space, the root cause is not always insufficient TEMP storage. Poorly optimized SQL statements, undersized temporary tablespaces, excessive parallelism, inadequate PGA memory, long-running sessions, or concurrent batch work...

ORA-00942: Table or View Does Not Exist – Complete Oracle DBA Troubleshooting Guide The ORA-00942: table or view does not exist error is one of the most frequently encountered Oracle Database errors by Database Administrators (DBAs), developers, Oracle Forms developers, Oracle APEX developers, Oracle E-Business Suite administrators, reporting teams, and application support engineers. The error occurs when Oracle cannot locate or access the specified table or view during SQL statement execution. Although the error message appears straightforward, ORA-00942 does not always indicate that the object is missing. In many production environments, the table or view actually exists, but Oracle cannot access it because of insufficient privileges, an incorrect schema reference, an invalid synonym, an unavailable database link, or execution under a different user context. Oracle resolves every referenced object through a well-defined object name resolution process. During SQL execut...

ORA-00001: Unique Constraint Violated in Oracle – Complete Fix Guide (Step-by-Step) The ORA-00001: unique constraint violated error is one of the most common issues faced by Oracle Database developers and DBAs. It occurs when an attempt is made to insert or update data that already exists in a column defined with a UNIQUE or PRIMARY KEY constraint. If you're dealing with this error, don’t worry—this guide will help you identify, troubleshoot, and permanently fix ORA-00001 using real-world solutions. What is ORA-00001 Error? The ORA-00001 error occurs when a duplicate value violates a uniqueness rule enforced by Oracle. In simple terms: You tried to insert a value that already exists Oracle blocked it to maintain data integrity Error Message ORA-00001: unique constraint (SCHEMA.CONSTRAINT_NAME) violated The message often includes the constraint name , which is your first clue to solving the problem. Quick Fix (Fast Solution) If you're in a hurry, follow this: ...

ORA-12154: TNS Could Not Resolve Connect Identifier Specified – Causes, Diagnosis, Solutions & Prevention Published: April 2026 Last Updated: July 2026 Reading Time: 12–15 Minutes Applies To: Oracle Database 11g, 12c, 18c, 19c, 21c and Oracle Database 23ai The ORA-12154: TNS Could Not Resolve Connect Identifier Specified error is one of the most common Oracle Net Services errors encountered by Database Administrators (DBAs), developers, application administrators, and Oracle E-Business Suite professionals. It occurs when Oracle Net cannot resolve the database connect identifier supplied by the client. This error may appear while connecting through SQL*Plus, SQL Developer, RMAN, Data Pump, Oracle Instant Client, JDBC applications, Oracle E-Business Suite, or other Oracle client tools. Although the error message appears simple, identifying the actual root cause often requires checking multiple configuration files, Oracle Net parameters, environment variables...