Software⏱️ 4 min read📅 2026-06-19

How to Fix: MS SQL Server 2012 Express Setup crashes with .NET error

MS SQL Server 2012 Express crashes with .NET error during installation on Windows Server 2008 R2 Enterprise SP1.

Quick Answer: Check if the .NET framework 3.5.1 feature is installed correctly and ensure that the System.Data assembly is not corrupted.

📋 Table of Contents

  1. 💡 Why You Are Getting This Error
  2. ✅ Best Solutions to Fix It
  3. 🎯 Final Words

The error 'Could not load file or assembly 'System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The module was expected to contain an assembly manifest.' occurs when the .NET framework 3.5.1 feature is not correctly installed or configured on the system. This error affects users attempting to install MS SQL Server 2012 Express on a Windows Server 2008 R2 Enterprise SP1 virtual machine.

This issue can be frustrating for IT professionals and administrators who rely on .NET framework 3.5.1 to install various software applications, including MS SQL Server 2012 Express. Fortunately, this error can often be resolved by troubleshooting the .NET framework installation and configuration.

💡 Why You Are Getting This Error

  • The primary reason for this error is that the .NET framework 3.5.1 feature was not installed correctly or is missing from the system. This could be due to incorrect installation, incomplete installation, or corrupted installation files.
  • An alternative cause of this error may be related to a conflicting application or service that prevents the .NET framework 3.5.1 from loading properly.

✅ Best Solutions to Fix It

Reinstalling and verifying .NET framework 3.5.1

  1. Step 1: Open the Control Panel and navigate to Programs and Features (or Add/Remove Programs in Windows XP). Ensure that the '.NET Framework 3.5' feature is listed and selected, then click 'Change' or 'Modify'. If the feature is not listed, download and install it from Microsoft's official website.
  2. Step 2: After reinstalling the .NET framework 3.5.1 feature, restart the system and attempt to run the SQL Server setup again. Verify that the feature has been successfully installed by checking for any updates in the Control Panel.
  3. Step 3: If the issue persists, try running the System File Checker (SFC) tool to scan for corrupted system files: Open the Command Prompt as an administrator, type 'sfc /scannow', and press Enter.

Checking for conflicts with other applications or services

  1. Step 1: Close all running applications and services on the system, including any antivirus software, to ensure that no conflicting applications are interfering with the .NET framework installation.
  2. Step 2: Restart the system in safe mode (by pressing F8 during boot-up) and attempt to run the SQL Server setup again. If the issue persists, this will help identify if a specific application or service is causing the conflict.

🎯 Final Words

To resolve the 'Could not load file or assembly' error when installing MS SQL Server 2012 Express, try reinstalling the .NET framework 3.5.1 feature and verifying its installation. If the issue persists, check for conflicts with other applications or services and attempt to run the SQL Server setup in safe mode.

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