The namespace "SYSTEM.WEB.MVC" does not exist in the type or namespace "Ajax" (is the assembly reference missing?)

Well, very excited to say that this problem has made me a night, the online posts are too few, as if not more than 2, and not very clear, and finally looked at a foreign one similar to

Forum website (called: Stack Flow), the result is still let me solve, although this point, but very excited, stay up to record this thing.

in ASP. NET MVC, you need to add a reference to the SYSTEM.WEB.MVC, but add a reference, or the problem arises, what is the cause of this problem, I guess

Because your current project is copied from another computer, want to study other people's Code, in others computer clearly run well, but to their own computer how can the problem? In fact, I also

Not very clear, presumably because these assemblies have not been copied over. Therefore, the first problem may occur when running, such as:

First of all, how to solve this situation, the solution is that you have to quote your native SYSTEM.WEB.MVC, add the reference, the new problem arises, that is, what to say today, error such as:

Obviously System.Web.Mvc.Ajax is in the System.Web.Mvc this namespace, but why still hint no reference? Cause I'm not quite sure at the moment,

Looking back at the deep research, and then modify this article, here first gives a solution: is set SYSTEM.WEB.MVC this DLL's property "Copy Local" set to true. The following two figures:

After set to true, clean up the solution (clear does not matter, I tried before is not clean, also can), and then run, the error disappears.

If it is in English, this property is copy Local = True. Well, the problem has finally been solved. Give it a good.

The namespace "SYSTEM.WEB.MVC" does not exist in the type or namespace "Ajax" (is the assembly reference missing?)