I am having a very similar problem to this: https://stackoverflow.com/questions/11023923/how-to-fix-this-mvc-website-error-could-not-load-file-or-assembly-system-web-h
same exact error message:
Could not load file or assembly 'System.Web.Helpers' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
I know this problem has to do with the upgrade from mvc3 to mvc4. My application is mvc3, but i installed mvc4 on my computer which is causing some sort of dependency issue. To fix this problem, I have to install mvc4 on my server to make it work, but with azure its a pain because none of my mvc4 installations stick to the server. Is there a way I can fix this so I don't have to install mvc4 everytime? or make it so my azure instance has it permanently installed. It's a real pain when I start deploying.