I am using ASP.NET MVC project with DLL built with LabVIEW 2015. The first call to any function would cause NullReferenceException. If the first exception was caught and ignored, subsequent call would no longer cause any exception. Below is the code snippet in HomeController.cs. Ping() is an empty vi. using System.Runtime.InteropServices;using foo;using NationalInstruments.LabVIEW.Interop;namespace WebApplication1.Controllers{ public class HomeController : Controller { public ActionResult Index() { foo__32API.Ping(); // An exception of type 'System.NullReferenceException' occurred in foo.dll but was not handled in user code return View(); }

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LabVIEW

NullReferenceException using LabVIEW DLL with ASP.NET MVC

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I did not have problem running with a standard windows console application. The NullReferenceException occurred with ASP.NET project with MVC template.

Below are the steps to create the project (also see the attached screenshots):

1) Select New Project -> Web -> ASP.NET Web Application

2) Select MVC under ASP.NET 4.5.2 Templates

3) Select Cancel in "Configure Microsoft Azure Web App

4) After the new project is created, browse under Solution Explorer -> Controllers -> HomeController.cs

5) Add the reference to the LV DLL in the Index() method (see code from message 3 in this topic)

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LabVIEW

NullReferenceException using LabVIEW DLL with ASP.NET MVC

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