Remember the weird problem with MVC4 site deployment on IIS

Recently, friends of the company encountered a site deployment problems, friends engaged in server maintenance for many years, said it took more than 10 days still to solve.

After several attempts failed, still error is as follows:

I asked about the situation and confirmed that the site was developed by VS2013, and that the version is, NET Framework4.5

In the "practice is the only criterion for testing truth", I let my friend pack a copy of the program for me.

Follow the routines set below, and the next is the time to witness miracles.

But,

Could not load file or assembly ' System.Web.Http 4.0.0

But the other MVC sites on the machine can be accessed normally??!

As an experienced programmer, and then immediately deployed a set of their own site,

Note that the IIS site configuration is identical and is also developed with vs2013.

Well, I promised to help, stay up to help solve it!

Start with a mistake, though I don't know what the error is saying ( Microsoft's tips have always been a bit of a fan of words haha)

Just google.

Finally found an IIS deployment MVC needed DLL, really solved the problem,

After the attempt to solve the problem

After all, the problem is solved, but still feel puzzled.

The machine has been installed vs2013 and 2015, supposedly the environment has been very perfect. Why is there a poor component?

Of course, the source of this site is the customer can not view, or would like to read carefully.

Remember the weird problem with MVC4 site deployment on IIS