How to get 'System.Web.Http, Version=5.2.3.0?

In Package Manager Console

Install-Package Microsoft.AspNet.WebApi.Core -version 5.2.3

PM> install-package microsoft.aspnet.webapi.core -version 5.2.3 Attempting to resolve dependency 'Microsoft.AspNet.WebApi.Client (≥ 5.2.3)'. Attempting to resolve dependency 'Newtonsoft.Json (≥ 6.0.4)'. 'Microsoft.AspNet.WebApi.Core 5.2.3' already installed. www.ptsol.com.au already has a reference to 'Microsoft.AspNet.WebApi.Core 5.2.3'.

One way to fix it is by modifying the assembly redirect in the web.config file.

Modify the following:

<dependentAssembly>
        <assemblyIdentity name="System.Net.Http.Formatting" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>

to

<dependentAssembly>
        <assemblyIdentity name="System.Net.Http.Formatting" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="4.0.0.0" />
</dependentAssembly>

So the oldVersion attribute should change from "...-4.0.0.0" to "...-5.2.3.0".

I did Install-Package Microsoft.AspNet.WebApi.Core -version 5.2.3 but it still did not work. Then looked in my project bin folder and saw that it still had the old System.Web.Mvc file.

So I manually copied the newer file from the package to the bin folder. Then I was up and running again.

Install-Package Microsoft.AspNet.WebApi.Core -version 5.2.3

Then in the project Add Reference -> Browse. Push the browse button and go to the C:\Users\UserName\Documents\Visual Studio 2015\Projects\ProjectName\packages\Microsoft.AspNet.Mvc.5.2.3\lib\net45 and add the needed .dll file

The packages you installed introduced dependencies to version 5.2.3.0 dll's as user Bracher showed above. Microsoft.AspNet.WebApi.Cors is an example package. The path I take is to update the MVC project proir to any package installs:

Install-Package Microsoft.AspNet.Mvc -Version 5.2.3

https://www.nuget.org/packages/microsoft.aspnet.mvc

Uninstalling and re-installing the NuGet package worked for me.

Remove any old reference from the project.

Execute this in the Package Manager Console:

UnInstall-Package Microsoft.AspNet.WebApi.Core -version 5.2.3 Install-Package Microsoft.AspNet.WebApi.Core -version 5.2.3

install this in your nuget package manager

Install-Package Microsoft.AspNet.WebApi.WebHost -Version 5.2.7

and paste

using System.Web.Http;

This should work