偶尔（约每月一次）的ASP.NET MVC 3 web应用程序失败与此异常。
System.NullReferenceException: Object reference not set to an instance of an object.
Server stack trace:
at System.Collections.Specialized.NameObjectCollectionBase.BaseGetAllKeys()
at System.Collections.Specialized.NameValueCollection.get_AllKeys()
at System.Web.WebPages.Scope.WebConfigScopeDictionary.<>c__DisplayClass4.<.ctor>b__0()
at System.Lazy`1.CreateValue()
Exception rethrown at [0]:
at System.Lazy`1.get_Value()
at System.Web.WebPages.Scope.WebConfigScopeDictionary.TryGetValue(Object key, Object& value)
at System.Web.Mvc.ViewContext.ScopeGet[TValue](IDictionary`2 scope, String name, TValue defaultValue)
at System.Web.Mvc.ViewContext.ScopeCache..ctor(IDictionary`2 scope)
at System.Web.Mvc.ViewContext.ScopeCache.Get(IDictionary`2 scope, HttpContextBase httpContext)
at System.Web.Mvc.ViewContext.GetClientValidationEnabled(IDictionary`2 scope, HttpContextBase httpContext)
at System.Web.Mvc.Html.FormExtensions.FormHelper(HtmlHelper htmlHelper, String formAction, FormMethod method, IDictionary`2 htmlAttributes)
at ASP._Page_Views_mywebpage_Create_cshtml.Execute() in c:\App\Views\Mywebpage\Create.cshtml:line 11
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.StartPage.ExecutePageHierarchy()
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
at System.Web.Mvc.Controller.ExecuteCore()
at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext)
at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5()
at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0()
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
上线会发生此异常
@using (Html.BeginForm())
从这个例外发生一次的时刻，应用程序无法使用。 每个视图将开始抛出这个错误。 我在源代码中环顾四周，但似乎无法找到任何东西。 还有谁遇到相同的行为，但与人不同的错误 ，并或通过不同的代码 。
当WebConfigScopeDictionary源更深的挖掘你可以看到的AppSettings正在读：
public WebConfigScopeDictionary() : this(WebConfigurationManager.AppSettings)
{
}
public WebConfigScopeDictionary(NameValueCollection appSettings)
{
this._items = new Lazy<Dictionary<object, object>>(() => appSettings.AllKeys.ToDictionary((string key) => key, (string key) => appSettings[key], ScopeStorageComparer.Instance));
}
该AppSettings的来自ConfigurationManager中：
public static NameValueCollection AppSettings
{
get
{
object section = ConfigurationManager.GetSection("appSettings");
if (section == null || !(section is NameValueCollection))
{
throw new ConfigurationErrorsException(SR.GetString("Config_appsettings_declaration_invalid"));
}
return (NameValueCollection)section;
}
}
如果将与web.config中有问题的代码应该抛出的异常。 但事实并非如此。 最终计数被称为在由AppSettings属性返回的集合。 因为它可能是空在这一点上它抛出。
protected string[] BaseGetAllKeys()
{
int count = this._entriesArray.Count;
string[] array = new string[count];
for (int i = 0; i < count; i++)
{
array[i] = this.BaseGetKey(i);
}
return array;
}
如果任何人有任何想法，随时分享。
