Assembly Conflict with Newtonsoft.Json
I got this problem today, I found the solution in this link.
Basically update the Newtonsoft.Json package. And register this assembly in the web.config
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" />
<bindingRedirect oldVersion="0.0.0.0-4.5.0.0" newVersion="5.0.8"/>
</dependentAssembly>
I had the same problem after installing SignalR to my project. First I updated to the latest version of Newtonsoft.Json, and then I add the dependentAssembly to my web.config. But I had to put the value of 6.0.0.0 in the new Version, even if in my packages I have version 6.0.8 declared.
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed"/>
<bindingRedirect oldVersion="0.0.0.0-4.5.0.0" newVersion="6.0.0.0"/>
</dependentAssembly>