Postmortem debugging with WinDBG

I have an WCF-service running on an server, and occasionally(1-2 times every month) it throws an COMException with the informative message ”Unknown error (0x8005008)”. When i googled for this particular error I only got threads about problems when creating virtual directories in IIS. And the source code hasn’t anything with making a virtual directory in IIS.

DirectoryServiceLib.LdapProvider.Directory - CreatePost - Could not create employee for 195001010000,000000000000: System.Runtime.InteropServices.COMException (0x80005008): Unknown error (0x80005008) at System.DirectoryServices.PropertyValueCollection.PopulateList

I've taken a memorydump when I catch the Exception for further analysis in WinDBG. After switching to the right thread I executed the !CLRStack command:

000000001b8ab6d8 000000007708671a [NDirectMethodFrameStandalone: 000000001b8ab6d8] Common.MemoryDump.MiniDumpWriteDump(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr)
000000001b8ab680 000007ff002808d8 DomainBoundILStubClass.IL_STUB_PInvoke(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr)
000000001b8ab780 000007ff00280812 Common.MemoryDump.CreateMiniDump(System.String)
000000001b8ab7e0 000007ff0027b218 DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String)
000000001b8ad6d8 000007fef8816869 [HelperMethodFrame: 000000001b8ad6d8] 
000000001b8ad820 000007feec2b6c6f System.DirectoryServices.PropertyValueCollection.PopulateList()
000000001b8ad860 000007feec225f0f System.DirectoryServices.PropertyValueCollection..ctor(System.DirectoryServices.DirectoryEntry, System.String)
000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String)
000000001b8ad8f0 000007ff00274d34 Common.DirectoryEntryExtension.GetStringAttribute(System.String)
000000001b8ad940 000007ff0027f507 DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost)
000000001b8ad980 000007ff0027a7cf DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String)
000000001b8adbe0 000007ff00279532 DirectoryServiceLib.WCFDirectory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String)
000000001b8adc60 000007ff001f47bd DynamicClass.SyncInvokeCreatePost(System.Object, System.Object[], System.Object[])

My conclusion is that it fails when the code is calling System.DirectoryServices.PropertyCollection.get_Item(System.String).

So after issuing an !CLRStack -a I get this result:

000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String)
   PARAMETERS:
      this = <no data>
      propertyName = <no data>
   LOCALS:
      <CLR reg> = 0x0000000001dcef78
      <no data>

My very first question is why does it display no data on the propertyname? I am kinda new on Windbg. However I executed an dumpobject on = 0x0000000001dcef78:

0:013> !do 0x0000000001dcef78
Name:        System.String
MethodTable: 000007fef66d6960
EEClass:     000007fef625eec8
Size:        74(0x4a) bytes
File:        C:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll
String:      personalprescriptioncode
Fields:
                  MT    Field   Offset                 Type VT     Attr            Value Name
000007fef66dc848  40000ed        8         System.Int32  1 instance               24 m_stringLength
000007fef66db388  40000ee        c          System.Char  1 instance               70 m_firstChar
000007fef66d6960  40000ef       10        System.String  0   shared           static Empty
                                 >> Domain:Value  0000000000174e10:00000000019d1420 000000001a886f50:00000000019d1420 <<

So when the source code wants to fetch the personalprescriptioncode from Active Directory(what is used for persistence layer) it fails. Looking back at the stack it is when issuing the Copy method. DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost)

So looking in the sourcecode:

DirectoryPost postInLimbo = DirectoryPostFactory.Instance().GetDirectoryPost(LdapConfigReader.Instance().GetConfigValue("LimboDN"), idGenPerson.ID.UserId);
if (postInLimbo != null)
   newPost.Copy(postInLimbo);

This code is looking for another post in OU=limbo with the same UserId and if it finds one it copies the attributes to the new post. In this case it does and it fails with personalprescriptioncode. I've looked in Active Directory under OU=Limbo and the post exist there with the attribute personalprescriptioncode=31243.

Question 1: Why does it display no data for some of the PARAMETERS and LOCALS? Is it the GC who has cleaned up before the memorydump had been created.

Question 2: Is there anymore i can do to get to the solution to this problem?

//
// MessageId: E_ADS_BAD_PARAMETER
//
// MessageText:
//
//  One or more input parameters are invalid
//
#define E_ADS_BAD_PARAMETER              _HRESULT_TYPEDEF_(0x80005008L)

You can't see the argument/local variable values because the code is optimized. They are stored in CPU registers at the time of the call, not the stack frame. You can't find the needle in the haystack anymore.