All my pages are giving me the following error.  How can I fix this?

Server Error in '/MyApplication' Application.

---

Object reference not set to an instance of an object.

[NullReferenceException: Object reference not set to an instance of an object.]
   Telerik.Sitefinity.Abstractions.VirtualPath.SitefinityPageResolver.AppendProperties(StringBuilder output, ObjectData ctrlData, Type ctrlType, CursorCollection placeHolders) +318
   Telerik.Sitefinity.Abstractions.VirtualPath.SitefinityPageResolver.BuildControls(PageData pageData, List`1 controlConatiners, CursorCollection placeHolders) +1604
   Telerik.Sitefinity.Abstractions.VirtualPath.SitefinityPageResolver.RenderPage(StringBuilder output, PageData pageData, RequestContext context, String virtualPath) +349
   Telerik.Sitefinity.Abstractions.VirtualPath.SitefinityPageResolver.Open(PathDefinition definition, String virtualPath) +253
   Telerik.Sitefinity.Abstractions.VirtualPath.VirtualPathManager.OpenFile(String virtualPath) +230
   System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) +255
   System.Web.UI.TemplateParser.Parse() +11197050
   System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() +135
   System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) +189
   System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() +265
   System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +46
   System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +580
   System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +619
   System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +203
   System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) +189
   System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) +56
   Telerik.Sitefinity.Web.PageRouteHandler.GetHttpHandler(RequestContext requestContext) +844
   System.Web.Routing.UrlRoutingModule.PostResolveRequestCache(HttpContextBase context) +11367992
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +266

Do you have custom widgets or layout controls?

yes to both

That's the problem I believe

I have a similar issue...they told me to execute this code

Steve, thank you so much for your reply.  My original error was something slightly different but after I resolved that, I immediately ran into the error you've graciously outlined for me.  

Have you been able to get your layouts working using what they've told you to do?  I added the virtual path configuration entry, changed all the layout property values to the new virtual path format, but now I just get " System.IO.FileNotFoundException: ~/my_assembly/my_assembly.Resources.ControlTemplates.Layouts.Main.ThreeColumn.ascx"  instead of the old "Invalid Layout Template".  


What's odd is that the layouts work fine in design mode and when I preview the page.  The problem arises on the live page.  

Wierd that you sent this just now...Im literally JUST trying to implement this this minute

I had the same issue...preview was fine, live was borked...thats why I figured we have the same problem.

This code needs an update through

So your global asax looks like this?

ALSO! 

If your layout controls have IDs specified you're supposed to remove those (the runat="server" ones) or impliment the (stupid) NamingContainer

So just a heads up too (after restoring my DB)

It seems that removing the IDs was the problem, had nothing to do with the code the agent sent me....so Im not even going to run that yet on this freshly restored db


**EDIT** scratch that, still needed to be run, but still getting yellow screens of death allover the place...4.1 is such a pain in the ass

- I did catch that the manager needed to call SaveChanges(), sorry I should have said something
- my global.asax does look just like that

still, my errors alternate between the "FileNotFound" and "Invalid layout template" screens.  

"If your layout controls have IDs specified you're supposed to remove those (the runat="server" ones) or impliment the (stupid) NamingContainer"  -- I don't quite understand what you mean here, do you mean to remove the IDs?

I have a day to make 4.1 work before we revert back to 4.0 sp1... thanks so much for all your input thus far, and I'd hugely appreciate it if you could keep this thread updated if you make any progress with this nastiness.  

Yeah I know all the documentation shows each Div in the layout needs an ID...but I am being told to remove the IDs...and really once I did the page RENDERED, but stuff was allover the place and edit mode shows me none of that content.  So it's got to be that SF wants to render content in Placeholder (layout) X, but that name doesn't exist anymore perhaps because the ID is gone.  So I have no doubt that starting from scratch this would all just work.  But I've spent the last few weeks creating the structure, entering content, and fixing URLs, and damned if I want to go back and do that AGAIN.

So screw it, back to the support tickets, maybe Radoslav has an idea...I don't want to have to go back through every page to fix everything...