Error when trying a "Differences" compare

Deane Barker

Vote:

When trying to do a "Differences" compare in v6 R1, I get a yellow screen of death with this:

Unable to cast object of type 'EPiServer.UI.Edit.PageCompare.Core.DummyWorkerRequest' to type 'System.Web.Hosting.IIS7WorkerRequest'.

Googling turns up nothing. I have this problem on two different installs.

Any ideas?

#50585

May 04, 2011 21:40

Vote:

Have you got the complete stacktrace from the errorscreen?

Looks like some internal asp.net-code expects the workerrequestobject we use to create the phony HttpContext in order to be able to render page's html to be of type IIS7WorkerRequest, which it's not. (its inheriting from HttpWorkerRequest).

/johan

#50589

May 04, 2011 23:35

Vote:

InvalidCastException: Unable to cast object of type 'EPiServer.UI.Edit.PageCompare.Core.DummyWorkerRequest' to type 'System.Web.Hosting.IIS7WorkerRequest'.]

System.Web.EtwTrace.Trace(EtwTraceType traceType, HttpWorkerRequest workerRequest, String data1, String data2, String data3, String data4) +284

System.Web.EtwTrace.Trace(EtwTraceType traceType, HttpWorkerRequest workerRequest, String data1, String data2) +27

System.Web.Profile.SqlProfileProvider.GetPropertyValuesFromDatabase(String userName, SettingsPropertyValueCollection svc) +168

System.Web.Profile.SqlProfileProvider.GetPropertyValues(SettingsContext sc, SettingsPropertyCollection properties) +505

System.Configuration.SettingsBase.GetPropertiesFromProvider(SettingsProvider provider) +400

System.Configuration.SettingsBase.GetPropertyValueByName(String propertyName) +216

System.Configuration.SettingsBase.get_Item(String propertyName) +102

System.Web.Profile.ProfileBase.GetInternal(String propertyName) +49

System.Web.Profile.ProfileBase.get_Item(String propertyName) +129

EPiServer.Globalization.SystemLanguage.LanguagePreferenceList(String priorityLanguage) +147

EPiServer.Globalization.SystemLanguage.SetCulture(String priorityLanguage) +22

EPiServer.PageBase.InitializeCulture() +86

ASP.templates_public_pages_page_aspx.__BuildControlTree(templates_public_pages_page_aspx __ctrl) in c:\Sites\TriWestCustomDev\Templates\Public\Pages\Page.aspx:1

ASP.templates_public_pages_page_aspx.FrameworkInitialize() in c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\1bacfcf8\e4708475\App_Web_hcu0qge4.4.cs:0

System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +72

System.Web.UI.Page.ProcessRequest() +119

System.Web.UI.Page.ProcessRequest(HttpContext context) +167

ASP.templates_public_pages_page_aspx.ProcessRequest(HttpContext context) in c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\1bacfcf8\e4708475\App_Web_hcu0qge4.4.cs:0

EPiServer.UI.Edit.PageCompare.Core.PageComparerProviderBase.GetHtmlByDummyRequest(String pageUrl) +463

EPiServer.UI.Edit.PageCompare.Core.PageComparerProviderBase.GetHtmlFromPage(PageData pageData) +34

EPiServer.UI.Edit.PageCompare.VisualPageCompare.GetHtmlDiff(PageReference first, PageReference second, Int32 firstVersionNumber, Int32 secondVersionNumber) +281

EPiServer.UI.Edit.PageCompare.VisualPageCompare.OnLoad(EventArgs e) +358

System.Web.UI.Control.LoadRecursive() +71

System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3048

#50590

May 05, 2011 0:03

Vote:

uhm yeah...

A quick run through ILSpy (now Reflectors gone commercial) reveals that some internal code in EtwTrace assumes the given HttpWorkerRequest can be casted to an II7WorkerRequest....

The problem is that the flag determining the type of the workerequest (s_wrType) is static, and it's set the first time it gets called, probably from a "normal" webrequest (which of course really *is* of type IIS7WorkerRequest):

internal static void Trace(EtwTraceType traceType, HttpWorkerRequest workerRequest, string data1, string data2, string data3, string data4)
{
	if (EtwTrace.s_WrType == EtwWorkerRequestType.Undefined)
	{
		EtwTrace.ResolveWorkerRequestType(workerRequest);
	}
	if (EtwTrace.s_WrType == EtwWorkerRequestType.Unknown)
	{
		return;
	}
	if (workerRequest == null)
	{
		return;
	}
	if (EtwTrace.s_WrType == EtwWorkerRequestType.IIS7Integrated)
	{
		UnsafeNativeMethods.TraceRaiseEventMgdHandler((int)traceType, ((IIS7WorkerRequest)workerRequest).RequestContext, data1, data2, data3, data4);
		return;
	}
	if (EtwTrace.s_WrType == EtwWorkerRequestType.InProc)
	{
		UnsafeNativeMethods.TraceRaiseEventWithEcb((int)traceType, ((ISAPIWorkerRequest)workerRequest).Ecb, data1, data2, data3, data4);
		return;
	}
	if (EtwTrace.s_WrType == EtwWorkerRequestType.OutOfProc)
	{
		UnsafeNativeMethods.PMTraceRaiseEvent((int)traceType, ((ISAPIWorkerRequest)workerRequest).Ecb, data1, data2, data3, data4);
	}
}

Personally, I think this is a bug with the EtwTrace-code,
and to be able to workaround, you would have to turn off tracing...

/johan

#50630

Edited, May 05, 2011 13:54

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Error when trying a "Differences" compare