Fixing the 'Could Not Load File or Assembly Microsoft Web Infrastructure' Error: A Step-by-Step Guide

This guide provides step-by-step instructions on how to resolve the "Could not load file or assembly 'Microsoft.Web.Infrastructure' or one of its dependencies" error in your .NET web application. This error typically occurs when the required dependency is missing from the project or not properly installed.

Table of Contents

  1. Prerequisites
  2. Step 1: Verify the Microsoft.Web.Infrastructure Package
  3. Step 2: Install the Required Package
  4. Step 3: Check Your Web.Config File
  5. Step 4: Rebuild and Test Your Application
  6. FAQs


Before you begin, make sure you have the following installed on your development machine:

  • Visual Studio (any version)
  • .NET Framework or .NET Core (depending on your project)
  • NuGet Package Manager

Step 1: Verify the Microsoft.Web.Infrastructure Package

To fix the "Could not load file or assembly 'Microsoft.Web.Infrastructure'" error, you must first verify whether the Microsoft.Web.Infrastructure package is installed in your project. To do this, follow these steps:

  1. Open your project in Visual Studio.
  2. In the Solution Explorer, right-click on the project and select "Manage NuGet Packages."
  3. Check if Microsoft.Web.Infrastructure is listed under the "Installed" tab.

If the package is not installed, proceed to Step 2 to install it.

Step 2: Install the Required Package

If the Microsoft.Web.Infrastructure package is missing from your project, you can easily install it using the NuGet Package Manager. Follow these steps to install the package:

  1. In the Solution Explorer, right-click on the project and select "Manage NuGet Packages."
  2. Click on the "Browse" tab.
  3. In the search box, type "Microsoft.Web.Infrastructure" and press Enter.
  4. Click on the Microsoft.Web.Infrastructure package in the search results.
  5. Click the "Install" button to install the package.

Note: You can also install the package using the Package Manager Console by running the following command:

Install-Package Microsoft.Web.Infrastructure

Step 3: Check Your Web.Config File

After installing the Microsoft.Web.Infrastructure package, you must ensure that your Web.Config file contains the necessary binding redirects. Check if the following lines are present in your Web.Config file:

  <assemblyIdentity name="Microsoft.Web.Infrastructure" publicKeyToken="31bf3856ad364e35" />
  <bindingRedirect oldVersion="" newVersion="" />

If you don't have these lines in your Web.Config file, add them inside the <runtime> section, like this:

  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <assemblyIdentity name="Microsoft.Web.Infrastructure" publicKeyToken="31bf3856ad364e35" />
      <bindingRedirect oldVersion="" newVersion="" />

Step 4: Rebuild and Test Your Application

Finally, rebuild your project by pressing Ctrl+Shift+B or by selecting "Build" > "Rebuild Solution" from the main menu. Then, run your application and verify that the "Could not load file or assembly 'Microsoft.Web.Infrastructure'" error has been resolved.


1. What is Microsoft.Web.Infrastructure?

Microsoft.Web.Infrastructure is a NuGet package that provides a set of general-purpose APIs that help to develop ASP.NET applications. This package is a dependency for many other popular packages, such as Microsoft.AspNet.Web.Optimization.

2. Can I use Microsoft.Web.Infrastructure with .NET Core?

No, Microsoft.Web.Infrastructure is designed to work with the .NET Framework. If you are developing a .NET Core application, you likely won't need this package.

3. What if I still get the error after following these steps?

If you still encounter the error after following the steps outlined in this guide, try cleaning your solution and deleting the bin and obj folders before rebuilding your project.

4. Are there any alternatives to Microsoft.Web.Infrastructure?

Microsoft.Web.Infrastructure is a dependency for specific packages and functionality in ASP.NET. If you don't need the features provided by those packages, you can remove them from your project and not use Microsoft.Web.Infrastructure.

5. Can I manually add the Microsoft.Web.Infrastructure DLL to my project?

While it is possible to manually add the DLL to your project, it is not recommended. Using NuGet to manage your project's dependencies is the best practice and ensures that you have the latest and compatible versions of the required packages.

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