Asp.Net MVC JsonResult 在 IIS 中抛出“缺少根元素”错误答案

【问题标题】：Asp.Net MVC JsonResult throwing 'Root element is missing' error in IISAsp.Net MVC JsonResult 在 IIS 中抛出“缺少根元素”错误
【发布时间】：2017-07-13 20:20:36
【问题描述】：

我有一个带有以下 JsonResult 的 MVC 5 Web 应用程序

public JsonResult GetCartSummary()
    {
        var cart = ShoppingCart.GetCart(HttpContext);
        var results = new ShoppingCartSummaryViewModel
        {
            CartTotal = cart.GetTotal(),
            CartCount = cart.GetCount()
        };
        return Json(results, JsonRequestBehavior.AllowGet);
    }

如果我在 IIS Express 或 Windows Azure 上进行本地测试，我会得到如下有效响应：

{"CartTotal":0,"CartCount":0}

但是当我将它上传到我们的生产服务器（在 Server 2012 R2 上运行的 IIS 8）时，它会引发以下异常：

Message: Root element is missing.
StackTrace:    at System.Xml.XmlTextReaderImpl.Throw(Exception e)
at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
at System.Xml.Linq.XDocument.Load(XmlReader reader, LoadOptions options)
at System.Xml.Linq.XDocument.Load(Stream stream, LoadOptions options)
at System.Data.Entity.Migrations.Edm.ModelCompressor.Decompress(Byte[] bytes)
at System.Data.Entity.Migrations.History.HistoryRepository.GetLastModel(String& migrationId, String& productVersion, String contextKey)
at System.Data.Entity.Internal.InternalContext.QueryForModel(DatabaseExistenceState existenceState)
at System.Data.Entity.Internal.ModelCompatibilityChecker.CompatibleWithModel(InternalContext internalContext, ModelHashCalculator modelHashCalculator, Boolean throwIfNoMetadata, DatabaseExistenceState existenceState)
at System.Data.Entity.Internal.InternalContext.CompatibleWithModel(Boolean throwIfNoMetadata, DatabaseExistenceState existenceState)
at System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context)
at System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action)
at System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization()
at System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input)
at System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action)
at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)
at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()
at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext()
at System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider()
at System.Linq.Queryable.Where[TSource](IQueryable`1 source, Expression`1 predicate)
at PlayingPlayers.Models.ShoppingCart.GetTotal()
at PlayingPlayers.Controllers.ShoppingCartController.GetCartSummary()
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<>c__DisplayClass2b.<BeginInvokeAction>b__1c()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult)
at System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Source: System.Xml
TargetSite: Void Throw(System.Exception)

我是否缺少需要上传的库，或者 IIS8 中是否有我缺少的设置？谢谢

【问题讨论】：

堆栈跟踪说它发生在cart.GetTotal()。我认为与 JSON 无关。看起来更像是迁移表中的模型数据存在问题。

标签： c# asp.net asp.net-mvc iis iis-8

【解决方案1】：

默认情况下，Server 2012 R2 使用 .net 版本 4.5.1。

您可能正在使用与服务器不兼容的最新版本的实体框架。我希望在服务器上安装最新的 .Net Framework 可以解决您的问题。试试这个https://www.microsoft.com/en-us/download/details.aspx?id=53344

【讨论】：