upgraded to 3.8 and now errors with razor

I have recently upgraded to 3.8 and now im faced with the following error :-

An error occurred creating the configuration section handler for system.web.webPages.razor/host: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

apparently the issue is with the following line :-

<section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />

how ever, this line doesnt actually exist in the config file.

ive googled and googled, and still cannot resolve the issue.

The site is installed on server 2008

any advise on this?

I am not certain, but I think this error is related to the fact that Microsoft.Web.Helpers for MVC 4 depends on System.Web.WebPages.Razor, Version=2.0.0.0..

Are you absolutely certain that the server which you just upgraded your site on does, in fact, have ASP.NET 4.5/MVC 4 installed on it? It seems like maybe not....the reference to the razor assembly is slightly different with MVC 4 than MVC 3..

all sorted now,  thank you..

For some reason,  i had to get the source, build it, and publish it.
Changed the config to allow managedcode, and it started to work. so not sure what happened in the downloaded release