Mono mod asp server web api post method not working

Question

I am trying to configure the mono modp asp server for webapi. It works fine with the get method, but the Post method gives me a weird error.

What I did was simply create the default webapi application and, without modifying it, use its default apicontroller.

Get and Post api works fine on the IIS server. I tried to find a solution, but got stuck very badly.

Please help me.