Decoding SQL Server Error 4064: A Deep Dive into Causes and Solutions

Summary: Microsoft SQL Server stands tall as a cornerstone for organizations seeking efficient data storage and retrieval capabilities. However, even the most robust systems encounter hurdles, and one such challenge that SQL Server users often grapple with is the enigmatic Error 4064. This elusive error, accompanied by messages like “Cannot open user default database. Login failed,” can bring a halt to seamless database interactions.

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In this comprehensive guide, we embark on a journey to demystify Microsoft SQL Server Error 4064. Beyond merely understanding the error code, we delve into the intricacies of its manifestations, exploring the underlying causes that lead to login failures and inaccessible default databases. From detached databases to orphaned users, misconfigured connection strings, and beyond, we dissect the common scenarios that pave the way for Error 4064.

SQL Server Error 4064

Our exploration extends to practical solutions, empowering administrators and developers to not only troubleshoot but also preemptively fortify their SQL Server environments against this formidable foe. Alongside conventional approaches such as database reattachment and user remapping, we shine a spotlight on the role of specialized tools, introducing the powerful Stellar Repair for MS SQL as a beacon of hope for scenarios involving severe database corruption.

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Understanding Microsoft SQL Server Error 4064:

Error 4064 occurs when a user attempts to connect to an SQL Server database and encounters a problem related to the default database. The error message “Cannot open user default database. Login failed” indicates that the default database specified for the user is inaccessible, leading to a failed login attempt.

1. Database Detachment:

  • Issue: The user’s default database might have been detached, leading to the inability to open it during login.
  • Solution: Reattach the database using SQL Server Management Studio (SSMS) or the sp_attach_db stored procedure.

2. Orphaned Users:

  • Issue: Orphaned users occur when a user is mapped to a database that no longer exists or is not accessible.
  • Solution: Use the sp_change_users_login stored procedure to fix orphaned users by updating the user’s SID (Security Identifier).

3. Connection String Misconfigurations:

  • Issue: Errors in the connection string, such as specifying a non-existent default database or using incorrect authentication details.
  • Solution: Review and correct the connection string settings, ensuring they align with the SQL Server configuration.

4. Stellar Repair for MS SQL:

Stellar Repair for MS SQL is a specialized tool designed to address severe database corruption issues. Here’s how it can help:

How Stellar Repair for MS SQL Addresses 4064 Error:

  1. Detection of Corruption: The tool performs a comprehensive scan of the SQL Server database, identifying and isolating areas affected by corruption.
  2. Reconstruction of Corrupted Elements: Stellar Repair for MS SQL reconstructs corrupted database elements, including tables, indexes, stored procedures, and triggers. This reconstruction process is crucial for restoring the functionality of the default database associated with the user login.
  3. Recovery of User-Specific Data: The tool ensures that user-specific data tied to the default database is recovered intact. This includes login credentials, permissions, and any other configurations associated with the user account.
  4. Creation of a Healthy Database: Once the repair process is complete, Stellar Repair for MS SQL creates a new, healthy version of the SQL Server database. This version is free from the corruption that led to the 4064 error.

Steps to Use Stellar Repair for MS SQL:

  1. Download and Installation: Download Stellar Repair for MS SQL tool from the official website and follow the installation instructions.
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  2. Database Selection: Launch the tool and select the corrupted SQL Server database experiencing the 4064 error.
  3. Scan and Preview: Initiate the scanning process to identify and assess the extent of database corruption. Preview the recoverable items to ensure accuracy.
  4. Repair and Recovery: Begin the repair process, allowing the tool to reconstruct and recover the corrupted elements. The tool will then create a healthy version of the database.
  5. Save the Repaired Database: Save the repaired database to the desired location. This is the version that can be used to replace the corrupted default database associated with the user login.

Also read, How to Restore Database from MDF File in SQL Server?

Best Practices to Avoid SQL Server Error 4064:

  1. Regular Backups: Implement a robust backup strategy to ensure that in the event of database corruption or loss, you can restore the system to its previous state.
  2. Database Maintenance Plans: Set up regular database maintenance plans to check for and address issues proactively, preventing the occurrence of errors like 4064.
  3. Documentation: Maintain comprehensive documentation for your SQL Server environment, including details about users, permissions, and database configurations.
  4. Monitor Event Logs: Regularly monitor SQL Server event logs for any warnings or errors that may indicate potential issues with the default database.

Also check, How to Recover SQL Server Database with Corrupt Log File?


Microsoft SQL Server Error 4064 requires a systematic approach to identify and resolve the root causes. By addressing common scenarios like database detachment, orphaned users, and connection string misconfigurations, administrators can enhance the reliability of their SQL Server instances. Additionally, tools like Stellar Repair for MS SQL offer a specialized solution for severe database corruption cases, providing a safety net for critical data. By following best practices and staying vigilant with maintenance tasks, organizations can minimize the risk of encountering Error 4064 and ensure the smooth operation of their SQL Server environments.

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