Could not load file or assembly 'Newtonsoft.Json'

Getting an error after upgrading to 1.6.2.1722 from 1.2.2.1455

Server Error in ‘/’ Application.
Could not load file or assembly ‘Newtonsoft.Json’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IO.FileLoadException: Could not load file or assembly ‘Newtonsoft.Json’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Assembly Load Trace: The following information can be helpful to determine why the assembly ‘Newtonsoft.Json’ could not be loaded.

WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

Stack Trace:

[FileLoadException: Could not load file or assembly ‘Newtonsoft.Json’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]

[FileLoadException: Could not load file or assembly ‘Newtonsoft.Json, Version=4.0.8.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0
System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks) +567
System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +192
System.Reflection.Assembly.Load(String assemblyString) +35
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +123

[ConfigurationErrorsException: Could not load file or assembly ‘Newtonsoft.Json, Version=4.0.8.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11569328
System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +485
System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +79
System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +337
System.Web.Compilation.BuildManager.CallPreStartInitMethods() +280
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1167

[HttpException (0x80004005): Could not load file or assembly ‘Newtonsoft.Json, Version=4.0.8.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed’ or one of its dependencies. The located assembly’s manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11702064
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4870277

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

I had to copy the dll manually into the bin directory on the IIS server to resolve the issue