.NET web application w3wp.exe issue

Hi Guys,

BACKGROUND:

We have one old .net web application.
It having simple .aspx pages and one master page.
Working in dev as well as production very well...

NEW FEATURE:

For some reason, we wanted to build the WEB API.
So we add it with the below process:
> ASP.NET Web Forms project 
> Add 
> Add Scaffolded Item 
> Web API 2 Controller with read/write actions
> Implemented one required controller
> test it from Visual Studio in DEV - WORKING
> test it by deploing in DEV - WORKING

ISSUE:

After deploying the same in production server, whole web application stop working.
TWO ERROS logs in eventviewer:

1) SOURCE - .NET Error

Application: w3wp.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an internal error in the .NET Runtime at IP 00007FF86AC5D0AD (00007FF86AC00000) with exit code 80131506.


2) SOURCE - Application Error

Faulting application name: w3wp.exe, version: 8.5.9600.16384, time stamp: 0x5215df96
Faulting module name: clr.dll, version: 4.6.1055.0, time stamp: 0x563c12de
Exception code: 0xc0000005
Fault offset: 0x000000000005d0ad
Faulting process id: 0xe18
Faulting application start time: 0x01d29d67c53a94d2
Faulting application path: c:\windows\system32\inetsrv\w3wp.exe
Faulting module path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\clr.dll
Report Id: 273589a4-0996-11e7-80d3-000d3ab07b23
Faulting package full name: 
Faulting package-relative application ID:

If I comment out the line "GlobalConfiguration.Configure(WebApiConfig.Register);"
Web Application start to work again in production - but without API!!


Any solution?