Oracle Error Reference - Common ORA- Errors & Solutions

This comprehensive reference provides detailed explanations and solutions for 78 common Oracle database errors. Each error entry includes root causes, diagnostic steps, and proven resolution methods tested in production environments.

🚨 Critical Production Errors

System & Instance Errors

ORA-00600: Internal Error - Oracle internal errors requiring support
ORA-00845: MEMORY_TARGET Not Supported - AMM startup failures
ORA-07445: Exception Encountered - Core dump errors and crashes
ORA-04031: Unable to Allocate Memory - Shared pool memory issues
ORA-04030: Out of Process Memory - PGA memory exhaustion
ORA-27125: Unable to Create Shared Memory - System resource allocation failures

Connection & Network Errors

ORA-12154: TNS Could Not Resolve - TNS name resolution failures
ORA-12514: TNS Listener Does Not Know - Service registration issues
ORA-12516: TNS No Available Handler - Connection pool exhaustion
ORA-12541: TNS No Listener - Listener connectivity problems
ORA-12519: No Appropriate Service Handler - Service handler issues

Space & Storage Errors

ORA-01653: Unable to Extend Table - Tablespace space issues
ORA-01654: Unable to Extend Index - Index tablespace problems
ORA-01688: Unable to Extend Table Partition - Partition space errors
ORA-01652: Unable to Extend Temp Segment - Temporary tablespace full
ORA-19815: Flash Recovery Area Full - FRA capacity exhaustion

Performance & Resource Errors

ORA-01555: Snapshot Too Old - Undo retention issues
ORA-00054: Resource Busy - Lock conflicts and busy resources
ORA-00060: Deadlock Detected - Transaction deadlocks
ORA-01000: Maximum Open Cursors - Cursor leak problems

PL/SQL & Development Errors

ORA-06512: At Line - PL/SQL error stack traces and debugging

📊 Error Categories by Severity

🔴 Critical (Immediate Action Required)

Error Code	Description	Business Impact
ORA-00600	Internal error	Database instability
ORA-07445	Exception/core dump	Instance crash risk
ORA-04031	Shared pool exhausted	Connection failures
ORA-01652	Temp space full	Query failures

🟡 High (Urgent Resolution Needed)

Error Code	Description	Business Impact
ORA-01555	Snapshot too old	Report failures
ORA-00054	Resource busy	Transaction delays
ORA-12519	No service handler	New connections blocked
ORA-01653	Cannot extend table	Insert/update failures

🟢 Medium (Plan Resolution)

Error Code	Description	Business Impact
ORA-01000	Max cursors exceeded	Application errors
ORA-00060	Deadlock detected	Transaction rollback
ORA-00001	Unique constraint	Data integrity
ORA-00942	Object not found	Query failures

🔍 Quick Diagnosis Tools

Error Pattern Analysis

-- Recent errors from alert log
SELECT originating_timestamp, message_text
FROM x$dbgalertext
WHERE message_text LIKE 'ORA-%'
  AND originating_timestamp > SYSTIMESTAMP - INTERVAL '1' DAY
ORDER BY originating_timestamp DESC;

-- Session errors
SELECT sid, serial#, username, sql_id,
       event, seconds_in_wait, state
FROM v$session
WHERE status = 'ACTIVE'
  AND wait_class != 'Idle';

-- Error frequency analysis
SELECT SUBSTR(message_text, 1, 9) as error_code,
       COUNT(*) as occurrences,
       MAX(originating_timestamp) as last_occurred
FROM x$dbgalertext
WHERE message_text LIKE 'ORA-%'
  AND originating_timestamp > SYSTIMESTAMP - INTERVAL '7' DAY
GROUP BY SUBSTR(message_text, 1, 9)
ORDER BY occurrences DESC;

Automated Error Monitoring

-- Create error tracking table
CREATE TABLE dba_error_log (
  error_timestamp TIMESTAMP DEFAULT SYSTIMESTAMP,
  error_code VARCHAR2(10),
  error_message VARCHAR2(4000),
  username VARCHAR2(30),
  program VARCHAR2(100),
  sql_id VARCHAR2(13),
  alert_sent CHAR(1) DEFAULT 'N'
);

-- Error capture trigger (example)
CREATE OR REPLACE TRIGGER capture_errors
AFTER SERVERERROR ON DATABASE
BEGIN
  IF ora_is_servererror(1555) OR
     ora_is_servererror(4031) OR
     ora_is_servererror(600) THEN
    INSERT INTO dba_error_log (
      error_code, error_message, username, program
    ) VALUES (
      'ORA-' || ora_server_error(1),
      ora_server_error_msg(1),
      ora_login_user,
      ora_client_ip_address
    );
    COMMIT;
  END IF;
END;
/

🛠️ Generic Resolution Strategies

Analyze memory usage

SELECT * FROM v$sgastat WHERE pool = 'shared pool' ORDER BY bytes DESC;
SELECT * FROM v$process_memory ORDER BY allocated DESC;

Adjust memory parameters

ALTER SYSTEM SET shared_pool_size = 2G SCOPE=BOTH;
ALTER SYSTEM SET pga_aggregate_target = 4G SCOPE=BOTH;

Check tablespace usage

SELECT tablespace_name,
       ROUND(used_space * 8192 / 1024 / 1024, 2) AS used_mb,
       ROUND(tablespace_size * 8192 / 1024 / 1024, 2) AS total_mb,
       ROUND(used_percent, 2) AS used_percent
FROM dba_tablespace_usage_metrics
ORDER BY used_percent DESC;

Add space or reorganize

ALTER TABLESPACE users ADD DATAFILE '/u01/oradata/users02.dbf' SIZE 10G;
ALTER TABLE large_table MOVE COMPRESS;

Verify listener status
Terminal window
```
lsnrctl status
lsnrctl services
```

Check connection limits

SELECT resource_name, current_utilization, max_utilization, limit_value
FROM v$resource_limit
WHERE resource_name IN ('processes', 'sessions');

📈 Proactive Error Prevention

Monitoring Scripts

-- Space monitoring
CREATE OR REPLACE PROCEDURE check_tablespace_usage AS
BEGIN
  FOR ts IN (
    SELECT tablespace_name, used_percent
    FROM dba_tablespace_usage_metrics
    WHERE used_percent > 85
  ) LOOP
    DBMS_OUTPUT.PUT_LINE('WARNING: ' || ts.tablespace_name ||
                        ' is ' || ts.used_percent || '% full');
  END LOOP;
END;
/

-- Memory monitoring
CREATE OR REPLACE PROCEDURE check_memory_usage AS
  v_shared_pool_free NUMBER;
BEGIN
  SELECT bytes INTO v_shared_pool_free
  FROM v$sgastat
  WHERE pool = 'shared pool' AND name = 'free memory';

  IF v_shared_pool_free < 100*1024*1024 THEN -- Less than 100MB
    DBMS_OUTPUT.PUT_LINE('CRITICAL: Shared pool free memory below 100MB');
  END IF;
END;
/

Best Practices for Error Prevention

Regular Maintenance
- Monitor space usage daily
- Review alert logs hourly
- Analyze AWR reports weekly
- Update statistics regularly
Capacity Planning
- Set up space alerts at 80% full
- Monitor connection pool usage
- Track memory consumption trends
- Plan for growth
Configuration Standards
- Set appropriate initialization parameters
- Configure automatic memory management
- Enable resumable space allocation
- Implement resource manager

🔗 Error Resolution Resources

Oracle Support Resources

My Oracle Support - Official knowledge base and patches
Oracle Documentation - Error message reference
Oracle Community - Peer support and discussions

Diagnostic Tools

ADRCI - Automatic Diagnostic Repository analysis
AWR Reports - Performance analysis around errors
Alert Log - Chronological error history
Trace Files - Detailed error diagnostics

Emergency Contacts

Oracle Support - For ORA-00600 and ORA-07445 errors
DBA Team - Internal escalation procedures
Management - Business impact assessment

📚 Using This Reference

Each error page includes:

Error explanation - What the error means
Common causes - Why it occurs
Diagnostic queries - How to investigate
Resolution steps - How to fix it
Prevention tips - How to avoid recurrence
Related errors - Similar issues to check

Navigate to specific error pages for detailed resolution guides tailored to each error scenario.