Experience Editor not working: Error while rendering sitecore shell cshtml files, null reference exception

Question

I'm working on a site that I've just inherited from another agency, which was recently upgraded from Sitecore 6.5 to 8.2. I just discovered that the page editor is not working. When I try to load the page editor, I get a server error and am unable to make any edits. There's a whole bunch of errors, I'll include the full error trace from when the page loads:

26548 10:35:09 ERROR Application error.
Exception: System.Web.HttpUnhandledException
Message: An unhandled exception occurred.
Source: Sitecore.Mvc
   at Sitecore.Mvc.Pipelines.MvcEvents.Exception.ShowAspNetErrorMessage.ShowErrorMessage(ExceptionContext exceptionContext, ExceptionArgs args)
   at Sitecore.Mvc.Pipelines.MvcEvents.Exception.ShowAspNetErrorMessage.Process(ExceptionArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Filters.PipelineBasedRequestFilter.OnException(ExceptionContext exceptionContext)
   at System.Web.Mvc.ControllerActionInvoker.InvokeExceptionFilters(ControllerContext controllerContext, IList`1 filters, Exception exception)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass3_1.<BeginInvokeAction>b__5(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
   at System.Web.Mvc.Controller.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
   at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
   at System.Web.Mvc.Controller.<>c.<BeginExecute>b__151_2(IAsyncResult asyncResult, Controller controller)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
   at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult)
   at System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult)
   at System.Web.Mvc.MvcHandler.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
   at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
   at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result)
   at Sitecore.Mvc.Routing.RouteHttpHandler.EndProcessRequest(IAsyncResult result)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Speak/Layouts/Layouts/Speak-Layout.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Presentation.RenderingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass3_6.<BeginInvokeAction>b__3()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass3_1.<BeginInvokeAction>b__5(IAsyncResult asyncResult)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Sitecore/ExperienceEditor/PageEditbar/PageEditBar.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.ProcessRenderRendering(Rendering rendering, TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.Render(String placeholderName, TextWriter writer, RenderPlaceholderArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.Process(RenderPlaceholderArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Helpers.SitecoreHelper.Placeholder(String placeholderName)
   at ASP._sitecore_shell_client_Speak_Layouts_Layouts_Speak_Layout_cshtml.Execute()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at RazorGenerator.Mvc.PrecompiledMvcView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Sitecore/Speak/Ribbon/Controls/Ribbon/Ribbon.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.ProcessRenderRendering(Rendering rendering, TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.Render(String placeholderName, TextWriter writer, RenderPlaceholderArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.Process(RenderPlaceholderArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Helpers.SitecoreHelper.Placeholder(String placeholderName)
   at Sitecore.ExperienceEditor.Speak.PageEditbar.PageEditBar.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.PageEditbar.ControlsExtension.PageEditBar(Controls controls, Rendering rendering, HtmlHelper`1 htmlHelper)
   at ASP._Page_sitecore_shell_client_Sitecore_ExperienceEditor_PageEditbar_PageEditBar_cshtml.Execute() in d:\Dev\CSCA\Website\sitecore\shell\client\Sitecore\ExperienceEditor\PageEditbar\PageEditBar.cshtml:line 4
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Sitecore/Speak/Ribbon/Controls/Strip/Strip.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.<>c__DisplayClass3.<RenderUsingPlaceholders>b__1(Rendering rendering)
   at Sitecore.Mvc.Extensions.EnumerableExtensions.Each[T](IEnumerable`1 source, Action`1 action)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderUsingPlaceholders(TextWriter output, ItemRenderer itemRenderer)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderItem(TextWriter output, Item item)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Ribbon.Ribbon.DoRender(HtmlTextWriter output)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.RibbonControlBase.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Ribbon.ControlsExtension.Ribbon(Controls controls, Rendering rendering)
   at ASP._Page_sitecore_shell_client_Sitecore_Speak_Ribbon_Controls_Ribbon_Ribbon_cshtml.Execute() in d:\Dev\CSCA\Website\sitecore\shell\client\Sitecore\Speak\Ribbon\Controls\Ribbon\Ribbon.cshtml:line 4
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Sitecore/Speak/Ribbon/Controls/Chunk/Chunk.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.<>c__DisplayClass3.<RenderUsingPlaceholders>b__1(Rendering rendering)
   at Sitecore.Mvc.Extensions.EnumerableExtensions.Each[T](IEnumerable`1 source, Action`1 action)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderUsingPlaceholders(TextWriter output, ItemRenderer itemRenderer)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderItem(TextWriter output, Item item)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Strip.Strip.DoRender(HtmlTextWriter output)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.RibbonControlBase.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Strip.ControlsExtension.Strip(Controls controls, Rendering rendering)
   at ASP._Page_sitecore_shell_client_Sitecore_Speak_Ribbon_Controls_Strip_Strip_cshtml.Execute() in d:\Dev\CSCA\Website\sitecore\shell\client\Sitecore\Speak\Ribbon\Controls\Strip\Strip.cshtml:line 4
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

Nested Exception

Exception: System.InvalidOperationException
Message: Error while rendering view: '/sitecore/shell/client/Sitecore/Speak/Ribbon/Controls/DeviceSimulators/DeviceSimulatorsButton/DeviceSimulatorsButton.cshtml' (model: 'Sitecore.Mvc.Presentation.RenderingModel, Sitecore.Mvc').

Source: Sitecore.Mvc
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Process(RenderRenderingArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.PipelineMethod.Invoke(Object[] parameters)
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.<>c__DisplayClass3.<RenderUsingPlaceholders>b__1(Rendering rendering)
   at Sitecore.Mvc.Extensions.EnumerableExtensions.Each[T](IEnumerable`1 source, Action`1 action)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderUsingPlaceholders(TextWriter output, ItemRenderer itemRenderer)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.RenderItem(TextWriter output, Item item)
   at Sitecore.Web.UI.Controls.Common.ItemRenderers.ItemRenderer.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Chunk.Chunk.DoRender(HtmlTextWriter output)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.RibbonControlBase.Render(HtmlTextWriter output)
   at Sitecore.Web.UI.Controls.ComponentBase.Render()
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.Chunk.ControlsExtension.Chunk(Controls controls, Rendering rendering)
   at ASP._Page_sitecore_shell_client_Sitecore_Speak_Ribbon_Controls_Chunk_Chunk_cshtml.Execute() in d:\Dev\CSCA\Website\sitecore\shell\client\Sitecore\Speak\Ribbon\Controls\Chunk\Chunk.cshtml:line 4
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

Nested Exception

Exception: System.ArgumentNullException
Message: Value cannot be null.
Parameter name: simulatorItem
Source: Sitecore.Kernel
   at Sitecore.Diagnostics.Assert.ArgumentNotNull(Object argument, String argumentName)
   at Sitecore.Shell.DeviceSimulation.Simulator..ctor(ID id, Database database)
   at Sitecore.Shell.DeviceSimulation.NoneSimulator..ctor(Database database)
   at Sitecore.Shell.DeviceSimulation.Simulator.Create(ID id, Database database)
   at Sitecore.Shell.DeviceSimulation.DeviceSimulationUtil.GetCurrentSimulator(Database database)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.DeviceSimulators.DeviceSimulatorsButton.DeviceSimulatorsButton.InitializeControl(RenderingParametersResolver renderingParametersResolver)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.RibbonButtonBase..ctor(RenderingParametersResolver parametersResolver)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.RibbonIconButtonBase..ctor(RenderingParametersResolver parametersResolver)
   at Sitecore.ExperienceEditor.Speak.Ribbon.Controls.DeviceSimulators.DeviceSimulatorsButton.ControlsExtension.DeviceSimulatorsButton(Controls controls, Rendering rendering)
   at ASP._Page_sitecore_shell_client_Sitecore_Speak_Ribbon_Controls_DeviceSimulators_DeviceSimulatorsButton_DeviceSimulatorsButton_cshtml.Execute() in d:\Dev\CSCA\Website\sitecore\shell\client\Sitecore\Speak\Ribbon\Controls\DeviceSimulators\DeviceSimulatorsButton\DeviceSimulatorsButton.cshtml:line 4
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Sitecore.Mvc.Presentation.ViewRenderer.Render(TextWriter writer)

The final error mentions the a null reference exception with simulatorItem in Sitecore.Kernel, which might be the root of the issue but I'm not sure what to do to resolve it.

I wouldn't rule out a botched upgrade. Might be worth the time to compare the DLLs and config files in your current instance with a vanilla install of 8.2u<?>. BeyondCompare or WinMerge should make quick work of this. — jrap, Commented Nov 2, 2018 at 15:01
Oh I am certain it was a botched upgrade. I'll do that, but do you know which DLLs or configs specifically I should be looking at? — Erica Stockwell-Alpert, Commented Nov 2, 2018 at 15:02
Stick to the stock ones and try to avoid any custom ones at first. Also Config Builder (version 3, marketplace.sitecore.net/Modules/S/…) is great for pinpointing config discrepancies. Choose the "Normalize" option and you'll get a nice alphabetized, nested output. — jrap, Commented Nov 2, 2018 at 15:06

Marek Musielak · Accepted Answer · 2018-11-03 15:38:25Z

From what I can see in your stack trace, you're missing None simulator item in your database.

Open Content Editor and check if you can search for item with ID {0F1228C5-631B-48FC-B17B-6175BEFEB2F5} or just expand content tree to /sitecore/layout/Simulators/None node:

If you confirm that the item is not there, you can in theory just create a package from a vanilla Sitecore install and deploy it to your website, but if that node is missing, there is high chance that other nodes are missing as well. Maybe it would be better idea to try to run the upgrade again and see if it works better?

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