C# SignInManager.PasswordSignInAsync引发空对象异常

AccountController.cs

包含

AccountController

类。该类的

Login

方法失败。具体来说,

var result=await-SignInManager.PasswordSignInAsync(
model.Email、model.Password、model.RememberMe、shouldllockout:true）；

在

Login

方法中，抛出

System.NullReferenceException

我已经验证了

model.Email

、

model.Password

和

model.RememberMe

不为空。下一步是深入到

SignInManager

，它是

AccountController

上类型为

ApplicationSignInManager

的对象。从上一行调用的

SignInManager

的

get

访问器无效

公共应用程序SignInManager SignInManager
{
得到
{
返回\u签名管理员？？
HttpContext.GetOwinContext（）.Get of
PasswordSignInAsync
，它在防止空引用错误方面做得非常好。我还深入研究了
PasswordSignInAsync
调用的方法。我根本看不到有什么可能抛出空引用错误

错误的堆栈跟踪非常隐晦，我看不出有什么帮助。但为了完整起见，这里是：

[NullReferenceException:对象引用未设置为对象的实例。]
Microsoft.AspNet.Identity.d_u0.MoveNext（）+2112
System.Runtime.CompilerServices.TaskWaiter.ThrowForNonSuccess（任务任务）+93
System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务）+52
System.Runtime.CompilerServices.TaskWaiter`1.GetResult（）+24
Microsoft.AspNet.Identity.CultureaWater`1.GetResult（）+123
Microsoft.AspNet.Identity.Owin.d__2.MoveNext（）+408
System.Runtime.CompilerServices.TaskWaiter.ThrowForNonSuccess（任务任务）+93
System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务）+52
System.Runtime.CompilerServices.TaskWaiter.GetResult（）+21
Microsoft.AspNet.Identity.CultureAwater.GetResult（）+63
Microsoft.AspNet.Identity.Owin.d_u23.MoveNext（）+2055
System.Runtime.CompilerServices.TaskWaiter.ThrowForNonSuccess（任务任务）+93
System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务）+52
System.Runtime.CompilerServices.TaskWaiter`1.GetResult（）+24
Microsoft.AspNet.Identity.CultureaWater`1.GetResult（）+68
Microsoft.AspNet.Identity.Owin.d_u29.MoveNext（）+1828
System.Runtime.CompilerServices.TaskWaiter.ThrowForNonSuccess（任务任务）+93
System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务）+52
System.Runtime.CompilerServices.TaskWaiter`1.GetResult（）+24
c:\Users\me\sc\project\Controllers\AccountController.cs:91中的ApexRemingtonExternal.Controllers.d\uu 2.MoveNext（）
System.Runtime.CompilerServices.TaskWaiter.ThrowForNonSuccess（任务任务）+93
System.Runtime.CompilerServices.TaskWaiter.HandleNonSuccessAndDebuggerNotification（任务）+52
System.Runtime.CompilerServices.TaskWaiter.GetResult（）+21
System.Threading.Tasks.TaskHelperExtensions.ThrowIfFaulted（任务）+61
System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute（IAsyncResult asyncResult）+114
System.Web.Mvc.Async.c__显示类37.b__36（IAsyncResult asyncResult）+66
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate（IAsyncResult asyncResult）+47
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End（）+136
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+102
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod（IAsyncResult asyncResult）+49
System.Web.Mvc.Async.AsyncInvocationWithFilters.b__3d（）+117
System.Web.Mvc.Async.c__DisplayClass46.b__3f（）+323
System.Web.Mvc.Async.c__显示类33.b__32（IAsyncResult asyncResult）+44
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate（IAsyncResult asyncResult）+47
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End（）+136
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+102
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters（IAsyncResult asyncResult）+50
System.Web.Mvc.Async.c__显示类2b.b__1c（）+72
System.Web.Mvc.Async.c__显示类21.b__1e（IAsyncResult asyncResult）+185
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate（IAsyncResult asyncResult）+42
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End（）+133
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+56
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction（IAsyncResult asyncResult）+40
System.Web.Mvc.Controller.b_u1d（IAsyncResult asyncResult，ExecuteCorerate innerState）+34
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate（IAsyncResult asyncResult）+70
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End（）+139
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+59
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+40
System.Web.Mvc.Controller.EndExecuteCore（IAsyncResult asyncResult）+44
System.Web.Mvc.Controller.b_uu15（IAsyncResult asyncResult，Controller-Controller）+39
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate（IAsyncResult asyncResult）+62
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End（）+139
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+59
System.Web.Mvc.Async.asyncResultRapper.End（IAsyncResult asyncResult，对象标记）+40
System.Web.Mvc.Controller.EndExecute（IAsyncResult asyncResult）+39
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute（IAsyncResult asyncResult）+39
System.Web.Mvc.MvcHandler.b_uu5（IAsyncResult asyncResult，ProcessRequestState innerState）+39
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate（IAsyncResult asyncResult）+70
System.Web.Mvc.Async.WrappedAs
public class ApplicationUser : IdentityUser
{
    ...//some additional properties goes here

    public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)
    {
        // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType
        var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);

        //my custom claims
        List<Claim> claims = new List<Claim>
        {
            new Claim("FirstName", FirstName.ToString()),
            new Claim("MiddleName", MiddleName.ToString()),
            new Claim("LastName", LastName.ToString()),
            new Claim("Position", Position.ToString()) //if Position is NULL, it will throw null reference exception
        };

        userIdentity.AddClaims(claims);

        return userIdentity;
    }
}