更改Sitefinity中的语言时出错

Question

我们有一个包含4种语言的网站。标准语言和英语。但不是其他人。出现以下错误：

[NullReferenceException: Object reference not set to an instance of an object.]
   Telerik.Sitefinity.Frontend.Resources.PackageManager.GetPackageFromNodeId(String nodeId) +400
   Telerik.Sitefinity.Frontend.Resources.PackageManager.GetPackageFromPageInfo() +742
   Telerik.Sitefinity.Frontend.Resources.PackageManager.GetCurrentPackage() +100
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Controllers.ControllerExtensions.GetKey(Controller controller) +320
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Controllers.ControllerExtensions.GetViewEngineCollection(Controller controller, Func`1 pathTransformationsFunc) +42
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Controllers.ControllerExtensions.UpdateViewEnginesCollection(Controller controller, Func`1 pathTransformationsFunc) +25
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Layouts.LayoutRenderer.CreateController(RouteData routeData) +333
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Layouts.LayoutRenderer.GetLayoutTemplate(String templateName, Boolean placeholdersOnly) +30
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Layouts.LayoutVirtualFileResolver.Open(PathDefinition definition, String virtualPath) +155
   Telerik.Sitefinity.Abstractions.VirtualPath.PageResolverBase.BuildWithMasterPage(String virtualPath, RequestContext context, StringBuilder output, CursorCollection placeHolders, DirectiveCollection directives) +77
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Layouts.<>c__DisplayClass2.<BuildWithMasterPage>b__0(Object[] args) +237
   Telerik.Sitefinity.Services.SystemManager.RunWithElevatedPrivilege(RunWithElevatedPrivilegeDelegate delegateToRun, Object[] parameters, String urlRequest) +439
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Layouts.LayoutMvcPageResolver.BuildWithMasterPage(String virtualPath, RequestContext context, StringBuilder output, CursorCollection placeHolders, DirectiveCollection directives) +234
   Telerik.Sitefinity.Mvc.Rendering.PureMvcPageResolver.RenderPage(StringBuilder sb, PageData pageData, RequestContext context, String virtualPath) +424
   Telerik.Sitefinity.Mvc.Rendering.PureMvcPageResolver.Open(PathDefinition definition, String virtualPath) +1084
   System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) +235
   System.Web.UI.TemplateParser.ParseInternal() +107
   System.Web.UI.TemplateParser.Parse() +195
   System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() +173
   System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) +132
   System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() +218
   System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +30
   System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +495
   System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +343
   System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +142
   System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) +11902614
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) +47
   Telerik.Sitefinity.Web.Compilation.CompilationHelpers.LoadControl(String virtualPath, Boolean isCausedByUserInteraction, PageSiteNode pageSiteNode) +364
   Telerik.Sitefinity.Web.PageRouteHandler.InstantiateHandler(RequestContext requestContext, PageSiteNode pageDataNode, String& theme) +220
   Telerik.Sitefinity.Web.PageRouteHandler.BuildHttpHandler(RequestContext requestContext) +683
   Telerik.Sitefinity.Frontend.Mvc.Infrastructure.Routing.MvcPageRouteHandler.BuildHttpHandler(RequestContext requestContext) +10
   System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context) +11995005
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +136
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +195
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +88

可能是什么原因？

问候安德烈亚斯