[c#] Could not load file or assembly 'Microsoft.Web.Infrastructure,

I tried to upload my web site to a server. It was working fine with my local host, so I uploaded everything in my localhost wwwroot folder to the server and changed the connection string.

But there is this error:

Exception information: 
    Exception type: InvalidOperationException 
    Exception message: The pre-application start initialization method Start on type RouteDebug.PreApplicationStart threw an exception with the following error message: Could not load file or assembly 'Microsoft.Web.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified..
   at System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods)
   at System.Web.Compilation.BuildManager.CallPreStartInitMethods()
   at System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException)

Could not load file or assembly 'Microsoft.Web.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
   at RouteDebug.PreApplicationStart.Start()

The project was nopcommerce.

What should be done to resolve this error?

It turns out after doing a Reference Cleaning, it removed Microsoft.Web.Infrastructure, but not from the packages.config file. After trying to add it again using the Package Manager Console, Visual Studio says that it is already installed which is false because it was removed.

I then removed the line of code in the packages.config file

<package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net45" />

and ran the command again

PM> Install-Package Microsoft.Web.Infrastructure

After this, now it works fine.

I had to set "Copy Local" in the Reference Properties to False, then back to True. Doing this added the Private True setting to the .csproj file.

<Reference Include="Microsoft.Web.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">      <HintPath>..\packages\Microsoft.Web.Infrastructure.1.0.0.0\lib\net40\Microsoft.Web.Infrastructure.dll</HintPath>
      <Private>True</Private>
    </Reference>

I had assumed this was already set, since the "Copy Local" showed as True.

For me Microsoft.Web.Infrastructure.dll was missing from the bin folder, it wasn't set to copy local in the project. Copied the dll from another project in the solution and the page loads.

In some cases cleaning the project/solution, physically removing bin/ and obj/ and rebuilding would resolve such errors. This could happen when, for example, some packages and references being installed/added and then removed, leaving some artifacts behind.

It happened to me with Microsoft.Web.Infrastructure: initially, the project didn't require that assembly. After some experiments, the net effect of which was supposed to be zero at the end, I got this exception. Above steps resolved it without the need to install unused dependency.

Experienced this issue on new Windows 10 machine on VS2015 with an existing project. Package Manager 3.4.4. Restore packages enabled.

The restore doesn't seem to work completely. Had to run the following on the Package Manager Command line

Update-Package -ProjectName "YourProjectName" -Id Microsoft.Web.Infrastructure -Reinstall

This made the following changes to my solution file which the restore did NOT do.

<Reference Include="Microsoft.Web.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <HintPath>..\packages\Microsoft.Web.Infrastructure.1.0.0.0\lib\net40\Microsoft.Web.Infrastructure.dll</HintPath>
  <Private>True</Private>
</Reference>

Just adding the above elements to the ItemGroup section in you solution file will ALSO solve the issue provided that ..\packages\Microsoft.Web.Infrastructure.1.0.0.0\lib\net40\Microsoft.Web.Infrastructure.dll exist.

Easier to just do the -Reinstall but good to understand what it does differently to the package restore.

First remove Microsoft.Web.Infrastructure from package.config.

and ran the command again

PM> Install-Package Microsoft.Web.Infrastructure and make sure Copy Local property should be true.

I found that even though it worked on my dev box, the assembly wasn't added to the project. Search for Microsoft.Web.Infrastructure in NuGet and install it from there. Then, make sure it has Copy Local selected.

Try installing Web Platform from https://www.microsoft.com/web/platform/

Hope it helps.

Despite the number of answers I'll add another one which IMHO makes the things a bit clearer.

As Rob and wrightmail already mentioned Microsoft.Web.Infrastructure is a NuGet package (link not needed, you have it in NuGet Package Manager).

Apparently, it was referenced by your project and suddenly disappeared. A number of reason may exists but the important thing is that despite you may have enabled Automatic Package Restore in Visual Studio by:

• Manage NuGet packages for solution (context menu in Solution Explorer),
• Allow NuGet to download missing packages (settings),
• Automatically check for missing packages during build in Visual Studio (settings),

certain packages may require a manual reinstall. I am not aware what confuses NuGet, maybe manually removing a reference, but here is the solution I usually apply in such cases. The following PM Console helps restoring a package while preserving the original version (not updating to possibly existing new one):

Update-Package Microsoft.Web.Infrastructure -Reinstall

Version preservation may be required if you do not want to accidentally overwrite an existing package with its newer version which possibly removes "old" functionality you may have used in your project.

And, as a proof, despite a bit lengthy one, that the version does not change, here's the output when the command is executed:

PM> Update-Package Microsoft.Web.Infrastructure -Reinstall
Attempting to gather dependencies information for multiple packages with respect to project 'Samples.NuGet\DemoApp\DemoApp', targeting '.NETFramework,Version=v4.5.2'
Attempting to resolve dependencies for multiple packages
Resolving actions install multiple packages
...
Package removal starts here...
...
Removed package 'Microsoft.AspNet.Web.Optimization 1.1.3' from 'packages.config'
Successfully uninstalled 'Microsoft.AspNet.Web.Optimization 1.1.3' from DemoApp
Removed package 'WebGrease 1.5.2' from 'packages.config'
Executing script file 'D:\Projects\DemoApp\packages\WebGrease.1.5.2\tools\uninstall.ps1'
Successfully uninstalled 'WebGrease 1.5.2' from DemoApp
...
More package removals here. Omitted for brevity...
...
Removed package 'Microsoft.Web.Infrastructure 1.0.0.0' from 'packages.config'
Successfully uninstalled 'Microsoft.Web.Infrastructure 1.0.0.0' from DemoApp
...
More package removals here. Omitted for brevity...
...
Removed package 'Antlr 3.4.1.9004' from 'packages.config'
Successfully uninstalled 'Antlr 3.4.1.9004' from MvcLenseApp
Package 'Antlr.3.4.1.9004' already exists in folder 'D:\Projects\Lense.Mvc5\packages'
--- Install packages (in reverse order) ---
Package 'Antlr.3.4.1.9004' already exists in folder 'D:\Projects\DemoApp\packages'
Added package 'Antlr.3.4.1.9004' to 'packages.config'
Successfully installed 'Antlr 3.4.1.9004' to DemoApp
...
More package installs here. Omitted for brevity...
...
Package 'Microsoft.Web.Infrastructure.1.0.0' already exists in folder 'D:\Projects\Lense.Mvc5\packages'
Added package 'Microsoft.Web.Infrastructure.1.0.0' to 'packages.config'
Successfully installed 'Microsoft.Web.Infrastructure 1.0.0' to MvcLenseApp
...
More package installs here. Omitted for brevity...
...
Package 'WebGrease.1.5.2' already exists in folder 'D:\Projects\DemoApp\packages'
Added package 'WebGrease.1.5.2' to 'packages.config'
Executing script file 'D:\Projects\DemoApp\packages\WebGrease.1.5.2\tools\install.ps1'
Successfully installed 'WebGrease 1.5.2' to DemoApp
Package 'Microsoft.AspNet.Web.Optimization.1.1.3' already exists in folder 'D:\Projects\DemoApp\packages'
Added package 'Microsoft.AspNet.Web.Optimization.1.1.3' to 'packages.config'
...
End of package re-install. 
...
Successfully installed 'Microsoft.AspNet.Web.Optimization 1.1.3' to DemoApp
PM> 

Of course if you wish to reinstall all packages you may need to get familiar with update/install commands in NuGet here and here.

Resharper detected Microsoft.Web.Infrastructure as an unused reference an so I deleted it. Locally was working fine but then I got the same error after publishing to dev.

Conclusion, beware when deleting references marked as unused by Resharper

Install AspNetMVC3ToolsUpdateSetup downloaded from here would solve this problem without adding reference

I don't know what happened with my project but it referenced the wrong path to the DLL. Nuget installed it properly and it was indeed on my file system along with the other packages but just referenced incorrectly.

The packages folder exists two directories up from my project and it was only going up one by starting the path with ..\packages\. I changed the path to start with ..\..\packages\ and it fixed my problem.

I had a similar problem. NuGet showed the package successfully installed, but the reference was not added to my project.

Running <PM> Install-Package Microsoft.Web.InfraStructure also didn't help as the package manager kept saying it's already installed

I finally added it manually by editing the csproj file and adding these lines:

 <Reference Include="Microsoft.Web.Infrastructure">
  <HintPath>..\packages\Microsoft.Web.Infrastructure.1.0.0.0\lib\net40\Microsoft.Web.Infrastructure.dll</HintPath>
  <Private>True</Private>
</Reference>

That solved the problem.

Very easy solution:

In Visual Studio, go to Tools/Library Package Manager/Package Manager Console

<PM> Install-Package Microsoft.Web.InfraStructure

Have a nice time

On my machine the Nuget dependency wasn't downloaded correctly, the lib folder inside the nuget package didn't exist, hence the error.

Before

I renamed the Nuget Package in the packages folder and Nuget redownloaded it correctly with the necessary lib folder.

After

So, here's what worked for me using VS2019. I was getting this error trying to update Nuget packages on one project while the Microsoft.Web.Infrastructure was in a different project in the same solution. I had to delete the Microsoft.Web.Infrastructure.1.0.0.0 folder from my project's Packages folder. Reinstalled it via nuget and then everything started working again. Crazy stuff.

You need to download the ASP.NET MVC framework on the server hosting your application. It's a quick fix just download and install from here (This is the MVC 3 framework http://www.asp.net/mvc/mvc3), then boom you are good to go.

I had this problem. I had the DLL included into the project and the setting to Copy Local was true by default. Don't know why it started, since that DLL was in the project for a long while. I've heard some mentions of ReSharper possibly removing it, but I can't say I've ran a unused reference removal.

What helped me was: - Running "Update-Package Microsoft.Web.Infrastructure -Reinstall" on the project, which updated the whole solution, but didn't end up helping in and of itself. - Then I went through the projects' references and set the Copy Local to false, and then back to true. This actually resulted in a line being added into CSPROJ file under the DLL reference: True. Or something along the lines... Either way, now the build was copying the files as expected.

Here was my scenario.

I had a multi project solution containing projects A, B, C .. N.

Project B was a code library that contained a factory for selectlist objects.

The project would run as expected in development, but when publishing to our test environment I was getting the error you were encountering:

Could not load file or assembly 'Microsoft.Web.Infrastructure, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

What had happened was through nuget package manager, I had accidentally installed "Microsoft ASP.NET MVC" which installed dependencies for:

• Microsoft.AspNet.Razor
• Microsoft.AspNet.WebPages

Low and behold, Microsoft.AspNet.WebPages depends on "Microsoft.Web.Infrastructure".

My solution was uninstalling the three packages mentioned above (MVC, Razor, WebPages) then right click references > add reference > Assemblies > Extensions > System.Web.MVC.