MVC 4 Web Api Controller does not have a default constructor?

You need to tell Ninject how to correctly resolve Web API dependencies.

You can use Felipe Oriani's answer, but if you like there is a NuGet package called WebApiContrib.IoC.Ninject which will do this for you.

1. In Visual Studio Go to: Tools > NuGet Package Manager > Manage NuGet Packages for Solution

2. Install the WebApiContrib.IoC.Ninject package

3. Edit: NinjectWebCommon.cs and update the CreateKernel() method to include: GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);

   private static IKernel CreateKernel()
   {
       var kernel = new StandardKernel();
   
       try
       {
           kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
           kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
   
           RegisterServices(kernel);
   
           //Note: Add the line below:
           GlobalConfiguration.Configuration.DependencyResolver = new NinjectResolver(kernel);
   
           return kernel;
       }
       catch
       {
           kernel.Dispose();
           throw;
       }
   }
   

This error is a known error when you do not set the dependency resolver in your application. The Controller Factory could not find a parameterless constructor to create the controller and execute the action method (or verb method?). So, you have to create a dependency resolver class and set it on the initialization of your web app. It will resolve dependencies of your controllers.

Using ninject, you could try something like this:

using Ninject; 
using Ninject.Syntax; 
using System; 
using System.Collections.Generic; 
using System.Diagnostics.Contracts; 
using System.Web.Http.Dependencies; 

namespace MyApplication.App_Start 
{     
    public class NinjectDependencyScope : IDependencyScope     
    {         
        private IResolutionRoot resolver;         

        internal NinjectDependencyScope(IResolutionRoot resolver)         
        {             
            Contract.Assert(resolver != null);             
            this.resolver = resolver;         
        }         

        public void Dispose()         
        {             
            IDisposable disposable = resolver as IDisposable;             
            if (disposable != null)                 
                disposable.Dispose();             
            resolver = null;         
        }         

        public object GetService(Type serviceType)         
        {             
            if (resolver == null)                 
                throw new ObjectDisposedException("this", "This scope has already been disposed");             

            return resolver.TryGet(serviceType);         
        }   

        public IEnumerable GetServices(Type serviceType)         
        {             
            if (resolver == null)                 
                throw new ObjectDisposedException("this", "This scope has already been disposed");             

            return resolver.GetAll(serviceType);         
        }     
    }     

    public class NinjectDependencyResolver : NinjectDependencyScope, IDependencyResolver     
    {         
        private IKernel kernel;         
        public NinjectDependencyResolver(IKernel kernel)             
            : base(kernel)         
        {             
            this.kernel = kernel;         
        }         

        public IDependencyScope BeginScope()         
        {             
            return new NinjectDependencyScope(kernel.BeginBlock());         
        }     
    } 
}

The NinjectDependencyResolver class takes a Ninject StandardKernel object as a constructor argument and this reference is used whenever a dependency scope is pipelined. To make this all work, the NinjectDependencyResolver class is assigned to the application's global configuration:

private static IKernel CreateKernel()
{
    var kernel = new StandardKernel();
    kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
    kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();

    // register all your dependencies on the kernel container
    RegisterServices(kernel);

    // register the dependency resolver passing the kernel container
    GlobalConfiguration.Configuration.DependencyResolver = new NinjectDependencyResolver(kernel);

    return kernel;
}

On your Global.asax.cs file in the end of Application_Start event, call this CreateKernel method.