ORA-00600: Internal Oracle Error Code – Complete Oracle DBA Troubleshooting Guide

The ORA-00600: Internal Oracle Error Code is one of the most serious Oracle Database errors that a Database Administrator (DBA) can encounter. Unlike configuration, networking, or SQL syntax errors, ORA-00600 indicates that the Oracle Database kernel has detected an unexpected internal condition. When this occurs, Oracle terminates the current operation to protect database integrity and records detailed diagnostic information for further analysis.

An ORA-00600 error does not necessarily mean that the database is corrupted. In many cases, it is triggered by Oracle software bugs, data block inconsistencies, memory corruption, hardware failures, operating system issues, or rare execution paths within the Oracle kernel.

Because ORA-00600 originates from Oracle's internal code, resolving it requires a structured troubleshooting approach rather than guessing or immediately restarting the database. Oracle automatically generates incident packages, trace files, and diagnostic information that can be analyzed by the DBA or submitted to Oracle Support for further investigation.

This comprehensive guide explains the ORA-00600 error, its arguments, common causes, production troubleshooting techniques, Oracle Automatic Diagnostic Repository (ADR), and best practices for Oracle Database 11g, 12c, 18c, 19c, 21c, and Oracle Database 23ai.

Quick Solution

Review the Oracle Alert Log and incident trace files immediately after ORA-00600 occurs. Identify the first argument of the error, collect diagnostic information using ADRCI, verify recent database or operating system changes, and search Oracle Support documentation for known issues or patches related to the reported argument.

Typical Error Message

ORA-00600: internal error code,
arguments: [kcratr_nab_less_than_odr],
[], [], [], [], [], [], []

Another example:

ORA-00600: internal error code,
arguments: [4194], [22], [20], [], [], [], [], []

The first argument is the most important part of the error because it identifies the Oracle kernel function or internal consistency check that failed.

What is ORA-00600?

ORA-00600 is a generic Oracle internal error generated when the Oracle Database kernel detects a condition that should never occur during normal operation. Instead of allowing the database to continue with potentially inconsistent data, Oracle stops the operation and records detailed diagnostic information.

Unlike user errors such as ORA-00942 (table or view does not exist) or ORA-01017 (invalid username/password), ORA-00600 indicates an internal Oracle problem that generally requires investigation by an experienced DBA and, in some cases, Oracle Support.

Oracle automatically creates an incident, writes diagnostic information to the Automatic Diagnostic Repository (ADR), and generates one or more trace files for analysis.

Understanding ORA-00600 Arguments

The ORA-00600 error contains several arguments enclosed in square brackets.

ORA-00600:
arguments:
[first_argument],
[second_argument],
[third_argument]...

Each argument provides additional information about the internal failure.

Argument	Description
First Argument	Internal Oracle function or consistency check that failed.
Second Argument	Oracle-specific diagnostic value.
Third Argument	Additional debugging information.
Remaining Arguments	Context-specific values used by Oracle Support.

For DBAs, the first argument is the most valuable because it can often be matched with Oracle Support notes, Release Updates (RUs), or known bugs.

Oracle Automatic Diagnostic Repository (ADR)

Beginning with Oracle Database 11g, Oracle introduced the Automatic Diagnostic Repository (ADR) to centralize diagnostic information.

Whenever ORA-00600 occurs, Oracle automatically stores:

Alert Log entries
Incident trace files
Core dump information (if applicable)
Health Monitor reports
Incident metadata
Packaging information for Oracle Support

Typical ADR location:

$ORACLE_BASE/diag/rdbms/
database_name/
instance_name/

Common Causes of ORA-00600

1. Oracle Software Bugs

The most common cause of ORA-00600 is an Oracle software defect. Oracle periodically releases Release Updates (RUs) and one-off patches that resolve known internal errors.

2. Data Block Corruption

Corrupted database blocks caused by storage failures, hardware issues, or incomplete writes may trigger internal consistency checks and generate ORA-00600.

3. Undo or Redo Corruption

Corruption within undo segments or redo logs may cause Oracle recovery processes to detect unexpected conditions.

4. Memory Corruption

Incorrect memory allocation, hardware memory faults, or software defects affecting the SGA or PGA can produce internal Oracle errors.

5. Hardware Failures

Faulty storage devices, failing disks, SAN issues, memory modules, or CPU faults may indirectly trigger ORA-00600.

6. Operating System Issues

Kernel bugs, filesystem corruption, insufficient shared memory, or operating system resource limitations may contribute to internal Oracle failures.

7. Failed Upgrade or Patch

Incomplete Oracle patching, failed upgrades, or incompatible binaries may introduce internal inconsistencies.

8. Oracle RAC or Cluster Events

In Oracle RAC environments, node eviction, Global Cache issues, or Clusterware failures can occasionally result in ORA-00600 incidents.

9. Data Dictionary Corruption

Corruption in Oracle's internal data dictionary structures may trigger consistency checks during SQL execution or database startup.

10. Rare Execution Paths

Certain combinations of SQL statements, optimizer decisions, PL/SQL packages, or parallel execution plans may expose rarely encountered Oracle kernel defects.

Common Symptoms

Unexpected database session termination.
Application failures.
ORA-03113 following ORA-00600.
Database instance crash.
Oracle background process termination.
Automatic incident creation.
Core dump generation.
Repeated internal errors in the Alert Log.

ORA-00600 Compared with Related Oracle Errors

Error	Description	Main Focus
ORA-00600	Internal Oracle kernel error.	Oracle Internal Processing
ORA-07445	Operating system exception encountered.	Server Process Crash
ORA-03113	End-of-file on communication channel.	Lost Client/Server Communication
ORA-04031	Unable to allocate shared memory.	Memory Management
ORA-01034	ORACLE Not Available.	Database Availability
ORA-27101	Shared Memory Realm Does Not Exist.	Instance Startup

Why ORA-00600 Should Never Be Ignored

Although some ORA-00600 incidents occur only once and never reappear, repeated occurrences often indicate an underlying problem that requires immediate attention. Ignoring the error may lead to repeated application failures, database instability, or data consistency issues.

Every ORA-00600 incident should be investigated by reviewing Oracle diagnostics before applying corrective actions. In production environments, documenting the incident, preserving trace files, and identifying recent environmental changes are essential steps before considering database restarts or recovery operations.

Production DBA Recommendation

Never treat ORA-00600 as an isolated message. The first error in the Alert Log, the ORA-00600 first argument, and the generated incident trace files usually contain the information needed to identify the root cause. Preserve these diagnostic files before restarting the instance, as they are often critical for troubleshooting and for opening a Service Request (SR) with Oracle Support.

Step-by-Step Troubleshooting ORA-00600

Troubleshooting ORA-00600 requires a structured approach. Since the error is generated internally by the Oracle kernel, randomly restarting the database or applying patches without understanding the root cause can make diagnosis much more difficult.

The following workflow reflects production best practices used by experienced Oracle DBAs.

Step 1 – Review the Oracle Alert Log

Always begin by reviewing the Oracle Alert Log immediately after the error occurs.

Typical location:

$ORACLE_BASE/diag/rdbms/<DB_NAME>/<INSTANCE_NAME>/trace/

alert_<SID>.log

Look for:

The first ORA-00600 entry
The first argument of the error
Related ORA errors
Database startup or shutdown events
Checkpoint activity
Redo log switches
Background process failures

Important DBA Tip

The first ORA-00600 error is usually the most valuable. Subsequent errors are often secondary symptoms.

Step 2 – Locate the Incident Trace File

Oracle automatically creates an incident trace file for every ORA-00600 occurrence.

Navigate to:

$ORACLE_BASE/diag/rdbms/

<database_name>/

<instance_name>/trace

Typical trace file:

prod1_ora_21456.trc

Review:

Error stack
Call stack
Current SQL statement
Current session
Memory dump
Process state
Wait events
Operating system information

Step 3 – Use ADRCI

Oracle's Automatic Diagnostic Repository Command Interpreter (ADRCI) simplifies incident investigation.

Start ADRCI:

adrci

Show diagnostic homes:

SHOW HOMES;

Set the desired ADR home:

SET HOMEPATH diag/rdbms/ORCL/ORCL1;

List incidents:

SHOW INCIDENT;

Review the incident associated with ORA-00600.

Step 4 – Package the Incident (IPS)

If Oracle Support assistance is required, create an Incident Packaging Service (IPS) package.

IPS CREATE PACKAGE;

IPS ADD INCIDENT 12345 PACKAGE 1;

IPS GENERATE PACKAGE 1;

The generated package contains the Alert Log, trace files, incident metadata, and diagnostic information required by Oracle Support.

Step 5 – Identify Recent Changes

Ask the following questions:

Was Oracle recently patched?
Was the operating system upgraded?
Were initialization parameters changed?
Was new application code deployed?
Was storage migrated?
Was the database recently upgraded?
Did hardware maintenance occur?

Many ORA-00600 incidents begin shortly after an environmental change.

Step 6 – Check Database Health

Verify overall database status.

SELECT

INSTANCE_NAME,

STATUS,

DATABASE_STATUS

FROM V$INSTANCE;

Confirm that all required background processes are running normally.

Step 7 – Check for Block Corruption

ORA-00600 may be associated with physical or logical block corruption.

Query corruption information:

SELECT *

FROM V$DATABASE_BLOCK_CORRUPTION;

If corruption exists, investigate recovery options using RMAN.

Step 8 – Verify Tablespaces and Datafiles

Confirm that all database files are available.

SELECT

FILE_ID,

FILE_NAME,

STATUS

FROM DBA_DATA_FILES;

Also verify:

Filesystem availability
ASM disk groups
NFS mounts
SAN connectivity

Step 9 – Review AWR Report

Generate an AWR report covering the time period immediately before ORA-00600 occurred.

Review:

Top Wait Events
Top SQL
CPU Usage
I/O Activity
Memory Statistics
Background Events
Database Time

Step 10 – Analyze ASH Report

ASH provides session-level activity leading up to the incident.

Look for:

Blocking sessions
High CPU SQL
Latch contention
Cursor activity
Object access patterns
Long-running transactions

Step 11 – Search Oracle Support

The first ORA-00600 argument often maps directly to known Oracle bugs.

Search using:

ORA-00600

[kcratr_nab_less_than_odr]

ORA-00600

[4194]

Oracle Support frequently provides:

Known bugs
Recommended patches
Release Updates (RU)
Workarounds
Recovery procedures

Step 12 – Oracle RAC Considerations

In Oracle RAC, determine whether the error occurred on one instance or multiple instances.

Verify cluster status:

srvctl status database

crsctl stat res -t

Also review:

Global Cache activity
Node evictions
Interconnect latency
Clusterware logs

Step 13 – Oracle Data Guard Considerations

If Data Guard is configured, verify:

Managed Recovery Process (MRP)
Redo Apply status
Archive Log transport
Broker status
Standby synchronization

An ORA-00600 during Redo Apply may indicate corruption or an Oracle software issue requiring further analysis.

Step 14 – Oracle Cloud Infrastructure (OCI)

For OCI-hosted databases, also review:

Compute instance health
Storage performance metrics
Block Volume health
Operating system logs
Memory utilization
VM or Exadata infrastructure events

Real Production Case Study

A production Oracle 19c database began generating intermittent ORA-00600 errors during nightly batch processing. The Alert Log showed the first argument [4194], and Oracle automatically generated an incident trace file.

The DBA reviewed the trace files, analyzed the AWR report, and confirmed that the issue began immediately after an interrupted storage maintenance activity. RMAN validation later detected corruption within several undo blocks.

The affected datafiles were recovered from backup, database consistency was verified, and the latest Oracle Release Update (RU) was applied. After recovery and patching, batch processing completed successfully with no further ORA-00600 incidents.

Production DBA Troubleshooting Checklist

Verification	Status
Alert Log Reviewed	☐
First ORA-00600 Argument Identified	☐
Incident Trace File Reviewed	☐
ADRCI Investigation Completed	☐
IPS Package Generated (if required)	☐
Recent Changes Reviewed	☐
Block Corruption Checked	☐
AWR/ASH Reports Reviewed	☐
RAC/Data Guard/OCI Reviewed (if applicable)	☐
Oracle Support Search Completed	☐
Root Cause Identified	☐

Oracle Version Considerations

The behavior of ORA-00600 has remained consistent across Oracle Database releases, but the diagnostic tools available to investigate it have improved significantly over time.

Oracle Version	Diagnostic Improvements
Oracle 10g	Basic trace files and Alert Log diagnostics.
Oracle 11g	Introduction of Automatic Diagnostic Repository (ADR), Incident Packaging Service (IPS), and Health Monitor.
Oracle 12c	Enhanced Multitenant (CDB/PDB) diagnostics and improved incident management.
Oracle 18c / 19c	Improved ADRCI commands, Health Monitor reports, and enhanced AWR diagnostics.
Oracle 21c / 23ai	Advanced diagnostics for cloud environments, Autonomous Database, and Oracle Cloud Infrastructure (OCI).

Understanding the ORA-00600 Diagnostic Process

When Oracle encounters an internal error, it follows a structured diagnostic process to preserve evidence for analysis.

Unexpected Internal Condition

           │

           ▼

Oracle Detects Internal Error

           │

           ▼

ORA-00600 Generated

           │

           ▼

Incident Created

           │

           ▼

Alert Log Updated

           │

           ▼

Trace File Generated

           │

           ▼

ADR Repository Updated

           │

           ▼

Incident Available for IPS Packaging

This automated process helps DBAs and Oracle Support investigate the incident without requiring manual data collection.

Using ADRCI for Incident Management

The Automatic Diagnostic Repository Command Interpreter (ADRCI) is one of the most valuable tools for investigating ORA-00600 incidents.

Common ADRCI commands:

adrci

SHOW HOMES

SET HOMEPATH diag/rdbms/ORCL/ORCL1

SHOW INCIDENT

SHOW PROBLEM

SHOW ALERT

SHOW TRACEFILE

IPS CREATE PACKAGE

IPS ADD INCIDENT

IPS GENERATE PACKAGE

These commands allow DBAs to review incidents, examine trace files, and prepare diagnostic packages for Oracle Support.

Useful Diagnostic SQL Queries

Check Instance Status

SELECT
INSTANCE_NAME,
STATUS,
DATABASE_STATUS
FROM V$INSTANCE;

Check Database Information

SELECT
NAME,
OPEN_MODE,
LOG_MODE
FROM V$DATABASE;

Check Background Processes

SELECT
NAME,
DESCRIPTION
FROM V$BGPROCESS
ORDER BY NAME;

Check Datafile Status

SELECT
FILE_ID,
FILE_NAME,
STATUS
FROM DBA_DATA_FILES;

Check Database Block Corruption

SELECT *
FROM V$DATABASE_BLOCK_CORRUPTION;

Review Invalid Database Objects

SELECT
OWNER,
OBJECT_NAME,
OBJECT_TYPE
FROM DBA_OBJECTS
WHERE STATUS='INVALID'
ORDER BY OWNER, OBJECT_NAME;

Common DBA Mistakes

Restarting the database before collecting diagnostic files.
Deleting trace files to free disk space before analysis.
Ignoring the first ORA-00600 argument.
Failing to review the Alert Log.
Applying random hidden (_) initialization parameters without Oracle Support guidance.
Ignoring recent operating system or storage changes.
Not validating backups before recovery operations.
Running repair scripts without understanding the root cause.
Delaying Release Updates (RUs) that contain known bug fixes.
Opening a Service Request without an IPS package or supporting diagnostics.

Oracle DBA Best Practices

Always preserve Alert Logs and trace files before restarting the instance.
Record the complete ORA-00600 error, including all arguments.
Use ADRCI to manage incidents instead of manually copying files.
Keep Oracle Release Updates (RUs) current.
Validate RMAN backups regularly.
Monitor storage, ASM, and filesystem health.
Review AWR and ASH reports after every critical incident.
Document environmental changes before and after maintenance.
Test Oracle patches in non-production environments before deployment.
Open a Service Request with Oracle Support when the root cause cannot be determined internally.

ORA-00600 Troubleshooting Workflow

ORA-00600 Occurs

        │

        ▼

Review Alert Log

        │

        ▼

Identify First Argument

        │

        ▼

Locate Trace File

        │

        ▼

Review Incident

        │

        ▼

Use ADRCI

        │

        ▼

Check Recent Changes

        │

        ▼

Review AWR / ASH

        │

        ▼

Validate Storage & Database Health

        │

        ▼

Search Oracle Support

        │

        ▼

Apply Patch / Recover / Resolve

        │

        ▼

Monitor Environment

Frequently Asked Questions (FAQ)

Is ORA-00600 always caused by an Oracle bug?

No. Although Oracle software bugs are a common cause, ORA-00600 may also result from data block corruption, undo or redo corruption, hardware failures, storage problems, operating system issues, or memory corruption.

Can restarting the database fix ORA-00600?

A restart may temporarily clear the symptom but rarely resolves the underlying cause. Diagnostic information should always be collected before restarting the instance.

What is the most important part of the ORA-00600 message?

The first argument inside the square brackets is the most important because it identifies the Oracle kernel component or consistency check that failed and is commonly used to search Oracle Support for known issues.

Where are ORA-00600 trace files stored?

Trace files are typically located in the Automatic Diagnostic Repository (ADR) under the database instance's trace directory within $ORACLE_BASE/diag/rdbms.

Should I delete trace files after the error?

No. Preserve all diagnostic files until the root cause has been identified or Oracle Support confirms they are no longer needed.

When should I contact Oracle Support?

If the error repeats, causes an instance crash, involves data corruption, or cannot be resolved through normal DBA troubleshooting, open a Service Request (SR) with Oracle Support and include an IPS package.

About the Author

Rana Abdul Wahid is an Oracle Database Consultant with more than 15 years of hands-on experience in Oracle Database Administration, Oracle RAC, Oracle Data Guard, RMAN Backup & Recovery, Oracle E-Business Suite, Oracle Cloud Infrastructure (OCI), Performance Tuning, Linux/Unix Administration, MySQL, Microsoft SQL Server, PostgreSQL, and enterprise database management.

Through this blog, he shares real-world Oracle DBA solutions, production troubleshooting guides, backup and recovery strategies, and performance tuning techniques to help database professionals resolve complex Oracle issues efficiently.

Learn more about the author →

Conclusion

The ORA-00600: Internal Oracle Error Code is one of the most critical Oracle Database errors because it indicates that the Oracle kernel has detected an unexpected internal condition. While the error itself can be alarming, it does not automatically mean that the database is corrupt. In many cases, the root cause is a known Oracle software bug, environmental issue, hardware problem, or data inconsistency that can be identified through careful analysis.

A disciplined troubleshooting process—including reviewing the Alert Log, analyzing incident trace files, using ADRCI, examining AWR and ASH reports, validating storage integrity, and checking recent environmental changes—enables DBAs to diagnose the problem accurately and minimize downtime.

Maintaining current Oracle Release Updates, validating backups, monitoring database health proactively, and preserving diagnostic information before taking corrective actions are essential practices for reducing the impact of ORA-00600 in production environments.

Final DBA Recommendation

Never attempt to resolve ORA-00600 by guessing or immediately restarting the database. Preserve the diagnostic evidence, identify the first ORA-00600 argument, collect an IPS package if necessary, and investigate the underlying cause methodically. A structured approach not only shortens recovery time but also prevents recurrence of the same internal error.

Found this guide helpful? Visit our Oracle Error Codes Guide for additional Oracle DBA tutorials, production troubleshooting guides, backup and recovery articles, and performance tuning best practices.

Oracle Database Error Solutions & DBA Knowledge Base