Question

我目前正在使用Visual Studio Express 2013 for Web构建一个网站，我正在使用默认的成员资格功能供用户注册。但是，当我在localhost上打开网站并尝试注册用户时，我收到以下错误：

An exception of type 'System.MissingMethodException' occurred in mscorlib.dll 
but was not handled in user code

Additional information: Method not found: 'System.Threading.Tasks.Task`1<!!0>
System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>,
System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.

以下是我浏览器的堆栈跟踪：

[MissingMethodException: Method not found: 'System.Threading.Tasks.Task`1<!!0> System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>, System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.]
   Microsoft.AspNet.Identity.EntityFramework.UserStore`6.GetUserAggregateAsync(Expression`1 filter) +0
   Microsoft.AspNet.Identity.EntityFramework.UserStore`6.FindByNameAsync(String userName) +1071
   Microsoft.AspNet.Identity.UserManager`2.FindByNameAsync(String userName) +177
   Microsoft.AspNet.Identity.<ValidateUserName>d__4.MoveNext() +803
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter.GetResult() +21
   Microsoft.AspNet.Identity.<ValidateAsync>d__0.MoveNext() +468
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
   Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +123
   Microsoft.AspNet.Identity.<CreateAsync>d__0.MoveNext() +795
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
   Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +123
   Microsoft.AspNet.Identity.<CreateAsync>d__d.MoveNext() +970
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
   Microsoft.AspNet.Identity.AsyncHelper.RunSync(Func`1 func) +409
   Microsoft.AspNet.Identity.UserManagerExtensions.Create(UserManager`2 manager, TUser user, String password) +260
   Account_Register.CreateUser_Click(Object sender, EventArgs e) in c:\Users\Matthew\Documents\College\Senior\CSE 448\Capstone\Capstone\Account\Register.aspx.cs:14
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9628026
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +103
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1724

抛出异常的代码标有星号：

protected void CreateUser_Click(object sender, EventArgs e)
    {
        var manager = new UserManager();
        var user = new ApplicationUser() { UserName = UserName.Text };

        *****IdentityResult result = manager.Create(user, Password.Text);
        if (result.Succeeded)
        {
            IdentityHelper.SignIn(manager, user, isPersistent: false);
            IdentityHelper.RedirectToReturnUrl(Request.QueryString["ReturnUrl"], Response);
        }
        else
        {
            ErrorMessage.Text = result.Errors.FirstOrDefault();
        }
    }

我一直在寻找，但似乎无法找到解决方案。我已经尝试更新我的所有参考文献，但无济于事。还有其他人遇到过这个吗？

Answer 1

知道了！ FirstOrDefaultAsync扩展方法仅存在于.Net 4.5实体框架程序集中。我在不同的项目中引用了.Net 4.0和.Net 4.5的混合物。当我将它们全部更改为.Net 4.5时，它可以使用Async代码。

Answer 2

使用上面的需要.Net 4.5实体框架程序集的答案，我仍然遇到了让Visual Studio识别新程序包的麻烦。相反，我刚刚打开NuGet包管理器，并“更新”到我目前使用的实体框架下面的一个版本（实体框架6.1.3 - ＆gt; 6.1.2）和.Net 4.5目标框架。

Answer 3

在程序包管理器控制台Install-Package System.Net.Http -Version 4.3.3上运行此程序

UserManager.Create：mscorlib.dll中出现“System.MissingMethodException”类型的异常，但未在用户代码中处理

3 个答案: