Common Error Codes

Understanding SQL Server Error Logs

SQL Server error logs are critical for diagnosing issues, tracking events, and troubleshooting problems. These logs contain detailed information about errors, warnings, and informational messages generated during server operations. Understanding common error codes within these logs is essential for effective troubleshooting.

Common Error Codes

SQL Server error codes are typically structured as [Error Code], with the first digit indicating the category (e.g., 100 for general errors, 104 for login-related issues). Below are key error codes and their explanations:

Connection and Authentication Errors

  • 100: General error (e.g., "Login failed for user 'xxx'").
  • 101: Invalid object name (e.g., "Invalid object name 'xxx'").
  • 102: Object not found (e.g., "Object not found in database 'xxx'").
  • 104: Login failed (e.g., "Login failed for user 'xxx'").
  • 105: Login not found (e.g., "Login 'xxx' not found").

Database and Object Issues

  • 108: Database does not exist (e.g., "Database 'xxx' does not exist").
  • 110: Invalid database name (e.g., "Invalid database name 'xxx'").
  • 111: Resource not found (e.g., "Resource not found in database 'xxx'").

Execution and Query Errors

  • 106: Login timeout (e.g., "Login timeout exceeded").
  • 107: Invalid password (e.g., "Invalid password for user 'xxx'").
  • 112: Object not found (e.g., "Object 'xxx' not found").

System and General Errors

  • 103: Database not found (e.g., "Database 'xxx' not found").
  • 113: Object not found (e.g., "Object 'xxx' not found").
  • 114: Object not found (e.g., "Object 'xxx' not found").

Error Code Examples

Error codes are often embedded in SQL Server logs, such as:

-- Example error log entry  
[2023-10-05 14:30:00] [ERROR] [104] Login failed for user 'invalid_user'.

These codes help identify the root cause of issues, such as incorrect credentials, missing databases, or failed queries.

Error Code Categories

Error codes can be categorized by severity and type:

  • Connection Errors: Related to login failures, timeouts, or invalid credentials.
  • Object Existence Errors: Involving missing tables, views, or databases.
  • Execution Errors: Caused by invalid queries, syntax errors, or permission issues.
  • System Errors: General errors like resource conflicts or disk space issues.

Resolving Common Error Codes

To resolve errors, follow these steps:

  1. Check the Error Code: Identify the specific code and its corresponding message.
  2. Review Logs: Use SQL Server Management Studio (SSMS) or the Windows Event Viewer to locate the log entry.
  3. Verify Permissions: Ensure the user has the necessary permissions for the database or object.
  4. Validate Object Names: Confirm that object names are spelled correctly and exist in the database.
  5. Check Network Settings: For connection errors, verify firewall rules and SQL Server instance configurations.

Conclusion

SQL Server error logs are indispensable for maintaining system stability and performance. By understanding and addressing common error codes, administrators can efficiently troubleshoot issues, prevent downtime, and optimize database operations. Regularly reviewing logs and staying informed about error codes ensures proactive maintenance and reduces the risk of critical failures.