Value cannot be null - Application Manager

Question

I was changing some things on a new startup file of a ASP.NET MVC site and I'm getting a null error:

System.ArgumentNullException: Value cannot be null. Parameter name: context

IdentityConfig file:

using -

using Microsoft.AspNet.Identity.Owin;
using Microsoft.AspNet.Identity;

...snip...

public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context) 
{
    var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<IdentityDb>()));
    // Configure validation logic for usernames
    manager.UserValidator = new UserValidator<ApplicationUser>(manager)
    {
        AllowOnlyAlphanumericUserNames = false,
        RequireUniqueEmail = true
    };

IdentityDb file :

public class IdentityDb : IdentityDbContext<ApplicationUser>
{
    public IdentityDb()
        : base("DefaultConnection")
    {
    }
}

I don't know if I am missing something with Microsoft.AspNet.Identity.Owin.IdentityFactoryProvider?

Server Error in '/' Application.

Value cannot be null. Parameter name: context

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentNullException: Value cannot be null.

Parameter name: context

Full Stack Trace :

Source Error: 


Line 40:         public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context)
Line 41:         {
Line 42:             var manager = new ApplicationUserManager(new UserStore<ApplicationUser>(context.Get<IdentityDb>()));
Line 43:             // Configure validation logic for usernames
Line 44:             manager.UserValidator = new UserValidator<ApplicationUser>(manager)

Source File: c:\users\aindriu\documents\visual studio 2015\Projects\Books\Books.Web\App_Start\IdentityConfig.cs    Line: 42 

Stack Trace: 


[ArgumentNullException: Value cannot be null.
Parameter name: context]
   Microsoft.AspNet.Identity.EntityFramework.UserStore`6..ctor(DbContext context) +335
   Microsoft.AspNet.Identity.EntityFramework.UserStore`1..ctor(DbContext context) +5
   Books.Web.ApplicationUserManager.Create(IdentityFactoryOptions`1 options, IOwinContext context) in c:\users\aindriu\documents\visual studio 2015\Projects\Books\Books.Web\App_Start\IdentityConfig.cs:42
   Microsoft.AspNet.Identity.Owin.IdentityFactoryProvider`1.Create(IdentityFactoryOptions`1 options, IOwinContext context) +14
   Microsoft.AspNet.Identity.Owin.<Invoke>d__0.MoveNext() +104
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<RunApp>d__5.MoveNext() +187
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<DoFinalWork>d__2.MoveNext() +185
   Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar) +69
   Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) +64
   System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +380
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Answer 1

To fix this problem I added app.CreatePerOwinContext(ApplicationDbContext.Create); to ConfigureAuth() in Startup.Auth.cs

Startup.Auth.cs

public partial class Startup
{
    // For more information on configuring authentication, please visit http://go.microsoft.com/fwlink/?LinkId=301864
    public void ConfigureAuth(IAppBuilder app)
    {
        // Configure the db context, user manager and signin manager to use a single instance per request
        app.CreatePerOwinContext(ApplicationDbContext.Create);
        app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);
        app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);

        // Enable the application to use a cookie to store information for the signed in user
        // and to use a cookie to temporarily store information about a user logging in with a third party login provider
        // Configure the sign in cookie
        app.UseCookieAuthentication(new CookieAuthenticationOptions
        {
            AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
            LoginPath = new PathString("/Account/Login"),
            Provider = new CookieAuthenticationProvider
            {
                // Enables the application to validate the security stamp when the user logs in.
                // This is a security feature which is used when you change a password or add an external login to your account.  
                OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, ApplicationUser>(
                    validateInterval: TimeSpan.FromMinutes(30),
                    regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
            }
        });            
        app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

        // Enables the application to temporarily store user information when they are verifying the second factor in the two-factor authentication process.
        app.UseTwoFactorSignInCookie(DefaultAuthenticationTypes.TwoFactorCookie, TimeSpan.FromMinutes(5));

        // Enables the application to remember the second login verification factor such as phone or email.
        // Once you check this option, your second step of verification during the login process will be remembered on the device where you logged in from.
        // This is similar to the RememberMe option when you log in.
        app.UseTwoFactorRememberBrowserCookie(DefaultAuthenticationTypes.TwoFactorRememberBrowserCookie);

        // Uncomment the following lines to enable logging in with third party login providers
        //app.UseMicrosoftAccountAuthentication(
        //    clientId: "",
        //    clientSecret: "");

        //app.UseTwitterAuthentication(
        //   consumerKey: "",
        //   consumerSecret: "");

        //app.UseFacebookAuthentication(
        //   appId: "",
        //   appSecret: "");

        //app.UseGoogleAuthentication(new GoogleOAuth2AuthenticationOptions()
        //{
        //    ClientId = "",
        //    ClientSecret = ""
        //});
    }
}