The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)?

I am trying to sort this annoying bug and I cant figure out the root cause of this exception. I went through the stack trace and still wasnt able to figure out the problem. I checked for he required dlls and everything looks fine to me. Any suggestions or advise is highly appreciated.

Stack Trace:-

[FileLoadException: The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)]
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName) +70
   System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +40
   System.Type.GetType(String typeName) +30
   System.Data.Common.DbProviderFactories.GetFactory(DataRow providerRow) +108
   System.Data.Common.DbProviderFactories.GetFactory(String providerInvariantName) +88
   System.Data.Entity.Infrastructure.DependencyResolution.DefaultProviderFactoryResolver.GetService(Type type, Object key, Func`3 handleFailedLookup) +77
   System.Data.Entity.Infrastructure.DependencyResolution.DefaultProviderFactoryResolver.GetService(Type type, Object key) +81
   System.Data.Entity.Infrastructure.DependencyResolution.<>c__DisplayClass1.<GetService>b__0(Tuple`2 k) +26
   System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +62
   System.Data.Entity.Infrastructure.DependencyResolution.CachingDependencyResolver.GetService(Type type, Object key) +140
   System.Data.Entity.Infrastructure.DependencyResolution.<>c__DisplayClass3.<GetService>b__0(IDbDependencyResolver r) +19
   System.Linq.WhereSelectArrayIterator`2.MoveNext() +58

C# code -

 public async Task<ActionResult> Register(RegisterViewModel model)
    {
        if (ModelState.IsValid)
        {
            var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
            var result = await UserManager.CreateAsync(user, model.Password);

            if (result.Succeeded)
            {
                await SignInManager.SignInAsync(user, isPersistent:false, rememberBrowser:false);

                // For more information on how to enable account confirmation and password reset please visit http://go.microsoft.com/fwlink/?LinkID=320771
                // Send an email with this link
                // string code = await UserManager.GenerateEmailConfirmationTokenAsync(user.Id);
                // var callbackUrl = Url.Action("ConfirmEmail", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
                // await UserManager.SendEmailAsync(user.Id, "Confirm your account", "Please confirm your account by clicking <a href=\"" + callbackUrl + "\">here</a>");

                return RedirectToAction("Index", "Home");
            }
            AddErrors(result);
        }

        // If we got this far, something failed, redisplay form
        return View(model);
    }

The exception is thrown at this specific line of code -

 public ApplicationUserManager UserManager
        {
            get
            {
                return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
            }
            private set
            {
                _userManager = value;
            }
        }

//The following method returns null and throws exception at return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();