Experience Sitecore! | Troubleshooting SXA "Failed to render rendering. Message: An unhandled exception occurred. Source: Sitecore.Mvc"

Experience Sitecore!

Martin Miles on Sitecore

Troubleshooting SXA "Failed to render rendering. Message: An unhandled exception occurred. Source: Sitecore.Mvc"

Got a weird exception, very similar to the one described at StackExchange (SXA Error when open page in Experience Editor). It happened at my CI server, so decided to reproduce locally, deploying on top of a clean instance of Sitecore, and got an issue reproduced.

Here's a call stack:

17264 22:03:56 ERROR Failed to render rendering
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.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.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.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
   at System.Web.Mvc.Controller.ExecuteCore()
   at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext)
   at Sitecore.Mvc.Controllers.ControllerRunner.ExecuteController(Controller controller)
   at Sitecore.Mvc.Controllers.ControllerRunner.Execute(TextWriter writer)
   at Sitecore.Mvc.Pipelines.Response.RenderRendering.ExecuteRenderer.Render(Renderer renderer, TextWriter writer, RenderRenderingArgs args)

Nested Exception

Exception: System.NullReferenceException
Message: Object reference not set to an instance of an object.
Source: Sitecore.XA.Foundation.Grid
   at Sitecore.XA.Foundation.Grid.Commands.ShowGridPropertiesDialog.QueryState(CommandContext context)
   at Sitecore.Shell.Framework.Commands.CommandManager.QueryState(Command command, CommandContext context)
   at Sitecore.Pipelines.GetChromeData.GetChromeDataProcessor.QueryButtonState(WebEditButton button, CommandContext context, String click)
   at Sitecore.Pipelines.GetChromeData.GetChromeDataProcessor.AddButtonToChromeData(WebEditButton button, GetChromeDataArgs args)
   at Sitecore.Pipelines.GetChromeData.GetChromeDataProcessor.AddButtonsToChromeData(IEnumerable`1 buttons, GetChromeDataArgs args)
   at Sitecore.Pipelines.GetChromeData.GetRenderingChromeData.Process(GetChromeDataArgs args)
   at (Object , Object )
   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.GetChromeData.GetChromeDataPipeline.Run(GetChromeDataArgs args)
   at Sitecore.Mvc.ExperienceEditor.Presentation.RenderingMarker.GetClientData()
   at Sitecore.Mvc.ExperienceEditor.Presentation.RenderingMarker.get_ClientData()
   at Sitecore.Mvc.ExperienceEditor.Presentation.RenderingMarker.GetStart()
   at Sitecore.Mvc.ExperienceEditor.Presentation.Wrapper..ctor(TextWriter writer, IMarker marker)
   at Sitecore.Mvc.ExperienceEditor.Pipelines.Response.RenderRendering.AddWrapper.Process(RenderRenderingArgs args)
   at (Object , Object )
   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.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Pipelines.Response.RenderPlaceholder.PerformRendering.Render(String placeholderName, TextWriter writer, RenderPlaceholderArgs args)
   at (Object , Object )
   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.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Helpers.SitecoreHelper.RenderPlaceholderCore(String placeholderName, TextWriter writer)
   at Sitecore.Mvc.Helpers.SitecoreHelper.Placeholder(String placeholderName)
   at ASP._Page_Views_Shared_Partial_Design_Dynamic_Placeholder_cshtml.Execute() in c:\inetpub\wwwroot\RssbPlatform.dev.local\Views\Shared\Partial Design Dynamic Placeholder.cshtml:line 5
   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.ViewResultBase.ExecuteResult(ControllerContext context)
   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.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

No single reference to my code, or whatsoever prompting to the actual reason.

Troubleshooting this was not an easy walk out. Logs also contained nothing relevant to the issue. Since I always keep at least daily backups done with a helpful tool Sif0n, it was relatively easy to substitute a web root folder from a fully functional solution. but the problem persisted. Then it is likely to be caused by something stored in a database.

I suspected something could be wrong with my serialization, I checked the settings but those were all correct. Then I restored fully functional database along with existing instance, calling it master_OK and started comparing those items one by one. And finally, I found the difference:


Reason for error: Rendering parameters template was missing due not being serialized and synced on that new environment. How could that happen? Don't know for sure, but a very alike suspect is that when using a clone rendering SXA script I accidentally missed out secondary options, so that script cloned rendering parameters for a new rendering, but left it underneath Experience Accelerator folder. Which is kept outside of serialization (as I more or less correctly predicted at the beginning of my investigation). So rendering parameters template was referenced, but did not exist on the target system. 

After fixing it, the site worked well. I do understand that the call stack I included above and the error messages are quite generic and may be met but any other scenarios, so probably Sitecore needs to assert and explicitly log such errors. At least I shared the way of dealing with it and my exact reason with you, hope it may help someone.

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