Have you seen a WebEngine.dll crash with ASP.Net 2.0? Read This...

Lately, I have received quite a few comments concerning a crash in WebEngine.dll when you recycle an application pool running ASP.Net 2.0.

The sheer number of independent users reporting this makes be believe that it is real. If it was individual users, I would think user hallucination (strangely, many users are very good at doing this... ;-) ), but when it comes with numbers and stack traces, I believe it and not mass hysteria.

However, I have yet to reproduce it myself given the provided instructions. One user said that merely making a request to an ASP.Net 2.0 page and then manual recycling the application pool should trigger the event... but that did not happen for me. Some have said that Sharepoint is involved; others see it without Sharepoint; I could not get either to work. The variations go on and on.

My Ask...

At the moment, I am a little short on bandwidth to figure out exactly what sequence results in the crash, so I am asking for some help in coming up with a reliable sequence of instructions that allow anyone to reproduce this crash. Be as detailed as possible. Start from when the OS is installed if you can - the more details of installation steps and in particular any non-default configuration changes (such as joining a domain, installing an application, running anti-virus, running login/configuration scripts, etc), the better. You want reliable, reproducible instructions because that allows a bug to be filed to the right developer to get it fixed.

What does this have to do with IIS7?

Now, the astute reader is probably wondering what ASP.Net 2.0 on IIS6 has anything to do with IIS7, so first let me give a little history of WebEngine.dll...

WebEngine.dll is a native code DLL which ships with ASP.Net 2.0 but also provides the managed code extensibility in IIS7. How it works is basically this:

• When used by ASP.Net 2.0/IIS6, Application Mappings of aspnet_isapi.dll funnel requests to ASP.Net, and aspnet_isapi.dll is simply a thin shim that calls into WebEngine.dll to create the AppDomains and drives the ASP.Net request pipeline.
• When used by IIS7, WebEngine.dll is loaded directly as a global module (native code only - see this blog entry for details) to create AppDomains, and it hooks directly into the IIS7 Integrated request Pipeline to provide managed code extensibility as the IIS7 request pipeline is driven.

Since IIS7 is in Windows Vista, and it comes with .Net Framework 2.0, it means that we had to get a foothold for our IIS7-related managed code extensibility and ship it with .Net Framework 2.0 ... which is why you see WebEngine.dll with ASP.Net 2.0 on IIS6 NOW instead of when IIS7 ships with Vista.

Of course, WebEngine.dll is not supposed to crash... and since its primary purpose is for IIS7, I am very interested in determining the cause because it may be an IIS7/Vista issue as well. The association of WebEngine.dll with an yet-to-ship product under active development (IIS7) instead of an already-shipped product under sustained engineering (ASP.Net 2.0) is what will make fixes in it happen faster.

So, if you are seeing crashes in WebEngine.dll with ASP.Net 2.0 NOW, I want to know about it. And if you can provide clear, reliable instructions for reproducing the crash, I thank you ahead of time for improving the quality of ASP.Net 2.0 and IIS7. And you should also thank yourself for getting a pesky issue fixed!

//David

Comments

• Anonymous
  March 16, 2006
  The comment has been removed

• Anonymous
  March 16, 2006
  Hi David,
  
  Could the "personal web server" that ships with Visual Studio 2005 be affected by this potential bug as well?  I remember once, during an hour-long investigation of difference between Cassini and the VS05 Web Server, thinking I found a reference from VS05 Web server and WebEngine.dll.
  
  Just a thought.
  
  Thanks,
  
  H

• Anonymous
  March 17, 2006
  The comment has been removed

• Anonymous
  March 17, 2006
  Harris - I don't know, but it would be easy to figure out.
  
  Have Cassini or the VS05 Personal Web Server running, then run the following command:
  
  TASKLIST.EXE /M WebEngine.dll
  
  And see if either of those processes have WebEngine.dll loaded. If they do, then maybe they are affected; otherwise, they are not.
  
  //david

• Anonymous
  March 21, 2006
  David,
  
  Thanks for the pointer; here's my results:
  
  myPath>tasklist /m webengine.dll
  
  Image Name                     PID         Modules
  ==========================================
  devenv.exe                       3568     webengine.dll
  WebDev.WebServer.EXE  2064      webengine.dll
  

• Anonymous
  April 07, 2006
  I have this on a 2003-SP1 fully patched server.
  
  Multiple sites and app pools all have this problem.
  
  I created a new site in IIS, created a new virtual dir in it's own app pool, created a new web project in vs2005, single default page, compile and published it to the server
  
  To crash IIS, hit default.aspx and then stop the app pool in the IIS manger and boom.  Letting the app pool time out has same effect.
  
  ModLoad: 5e380000 5e409000   C:WINDOWSMicrosoft.NETFrameworkv2.0.50727diasymreader.dll
  (10d4.1b8c): CLR exception - code e0434f4d (first chance)
  (10d4.1b8c): C++ EH exception - code e06d7363 (first chance)
  (10d4.1b8c): CLR exception - code e0434f4d (first chance)
  (10d4.1b8c): CLR exception - code e0434f4d (first chance)
  (10d4.1b8c): CLR exception - code e0434f4d (first chance)
  (10d4.1b8c): C++ EH exception - code e06d7363 (first chance)
  (10d4.1b8c): C++ EH exception - code e06d7363 (first chance)
  (10d4.1fd8): Access violation - code c0000005 (first chance)
  First chance exceptions are reported before any exception handling.
  This exception may be expected and handled.
  eax=800703e3 ebx=00000001 ecx=019b2710 edx=019b3a50 esi=006f004c edi=000003e3
  eip=6a2a2fec esp=0139fc20 ebp=000ce4b8 iopl=0         nv up ei ng nz na pe nc
  cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010282
  webengine!CorThreadPoolCompletionCallback+0x32:
  6a2a2fec ff560c           call  dword ptr [esi+0xc] ds:0023:006f0058=????????
  
  Stephen
  s i w at g t l dot b i z
  
   

• Anonymous
  April 11, 2006
  The comment has been removed

• Anonymous
  April 17, 2006
  The comment has been removed

• Anonymous
  April 17, 2006
  I just completely reinstalled .NET 1.0 and .Net 2.0.  Still blows up.  It brings up the FIRST page in my application - the login page - it takes the normal 20 seconds or so to come up as the site is compiled.  But then when i try to login or go to any other page in the site, it just spins with little or no disk activity until crashing about 30-45 seconds later.  
  
  This happens with every single ASP.NET 2.0 site.  If I create an empty site with nothing but a single page I can make it happen every single time simply by trying to browse to the site.

• Anonymous
  April 17, 2006
  The comment has been removed

• Anonymous
  April 20, 2006
  We get a crash one to three times a day.  Since I noticed it, I've started using IISDiag and have collected a dump file for analysis. The crash is in trying to access memory at an address that seems like it is probably outside physical memory.
  
  In w3wp__PID__3212__Date__04_19_2006__Time_11_07_02PM__495__Second_Chance_Exception_C0000005.dmp the module ?C:WINDOWSMicrosoft.NETFrameworkv2.0.50727webengine.dll has caused an access violation exception (0xC0000005) when trying to read from memory location 0x00650068 on thread 15
  
  Table Of Contents
  w3wp__PID__3212__Date__04_19_2006__Time_11_07_02PM__495__Second_Chance_Exception_C0000005.dmp
  
    Faulting Thread
  
  
  
  
  Report for w3wp__PID__3212__Date__04_19_2006__Time_11_07_02PM__495__Second_Chance_Exception_C0000005.dmp
  Type of Analysis Performed   Crash Analysis
  Machine Name   WEB-STAGE
  Operating System   Windows Server 2003 Service Pack 1
  Number Of Processors   2
  Process ID   3212
  Process Image   c:WINDOWSsystem32inetsrvw3wp.exe
  System Up-Time   12 day(s) 12:16:15
  Process Up-Time   0 day(s) 09:54:16
  
  
  Thread 15 - System ID 5556
  Entry point   mscorwks!Thread::intermediateThreadProc
  Create time   4/19/2006 4:03:15 PM
  Time spent in user mode   0 Days 0:0:0.62
  Time spent in kernel mode   0 Days 0:0:0.46
  
  
  
  
  
  
  Function     Arg 1     Arg 2     Arg 3   Source
  650068     01892710     800703e3     00000000    
  webengine!CorThreadPoolCompletionCallback+35     000003e3     00000000     01893390    
  mscorwks!ThreadpoolMgr::CompletionPortThreadStart+406     00000000     eda68aa0     00000000    
  mscorwks!Thread::intermediateThreadProc+49     0ea862c0     00000000     00000000    
  kernel32!BaseThreadStart+34     79ecafc5     0ea862c0     00000000    
  
  
  
  
  In w3wp__PID__3212__Date__04_19_2006__Time_11_07_02PM__495__Second_Chance_Exception_C0000005.dmp the module ?C:WINDOWSMicrosoft.NETFrameworkv2.0.50727webengine.dll has caused an access violation exception (0xC0000005) when trying to read from memory location 0x00650068 on thread 15
  
  Module Information
  Image Name: ?C:WINDOWSMicrosoft.NETFrameworkv2.0.50727webengine.dll   Symbol Type:  PDB
  Base address: 0x6a2a0000   Time Stamp:  Fri Sep 23 05:53:08 2005  
  Checksum: 0x0004a774   Comments:  Flavor=Retail
  COM DLL: False   Company Name:  Microsoft Corporation
  ISAPIExtension: False   File Description:  Microsoft ASP.NET Support DLL
  ISAPIFilter: False   File Version:  2.0.50727.42 (RTM.050727-4200)
  Managed DLL: False   Internal Name:  webengine.dll
  VB DLL: False   Legal Copyright:  © Microsoft Corporation. All rights reserved.
  Loaded Image Name:  webengine.dll   Legal Trademarks:  
  Mapped Image Name:     Original filename:  webengine.dll
  Module name:  webengine   Private Build:  
  Single Threaded:  False   Product Name:  Microsoft® .NET Framework
  Module Size:  304.00 KBytes   Product Version:  2.0.50727.42
  Symbol File Name:  c:symcachewebengine.pdb2EDCD5DD03B24BC4BAD6ACEBA4A4AB972webengine.pdb   Special Build:  &
  

• Anonymous
  April 20, 2006
  David
  
  Very pleased to hear someone at MS is at last interested in this crash scenario.
  
  Below is what I get from Debug Diagnostic Tool.
  
  It occurs when the AppPool recycles and is in WebEngine.dll referencing memory getting an access violoation.
  
  I have seent he posts about the Names registry settings but this is not a domain controller.
  
  It is very hard to reproduce this error, a machine either gets it or it does not. Sometimes same hardware and build, different servers have it some do not.
  
  -----------------------------------------
  
  w3wp__PID__1836__Date__04_21_2006__Time_12_14_49PM__562__Second_Chance_Exception_C0000005.dmp
  
  Type of Analysis Performed   Crash Analysis
  Machine Name   UKXXLON20AP0004
  Operating System   Windows Server 2003 Service Pack 1
  Number Of Processors   2
  Process ID   1836
  Process Image   c:WINDOWSsystem32inetsrvw3wp.exe
  System Up-Time   90 day(s) 23:38:19
  Process Up-Time   0 day(s) 00:08:04
  
  
  Thread 8 - System ID 1296
  Entry point   mscorwks!ThreadpoolMgr::intermediateThreadProc
  Create time   21/04/2006 12:06:49
  Time spent in user mode   0 Days 0:0:0.0
  Time spent in kernel mode   0 Days 0:0:0.0
  
  Function     Arg 1     Arg 2     Arg 3   Source
  webengine!CorThreadPoolCompletionCallback+32     000003e3     00000000     018c31d8    
  mscorwks!ThreadpoolMgr::CompletionPortThreadStart+406     00000000     00000000     f485ad08    
  mscorwks!ThreadpoolMgr::intermediateThreadProc+49     000d3b70     00000000     00000000    
  kernel32!BaseThreadStart+34     79f710dd     000d3b70     00000000    
  
  
  WEBENGINE!CORTHREADPOOLCOMPLETIONCALLBACK+32In w3wp__PID__1836__Date__04_21_2006__Time_12_14_49PM__562__Second_Chance_Exception_C0000005.dmp the assembly instruction at webengine!CorThreadPoolCompletionCallback+32 in ?C:WINDOWSMicrosoft.NETFrameworkv2.0.50727webengine.dll from Microsoft Corporation has caused an access violation exception (0xC0000005) when trying to read from memory location 0x006f0058 on thread 8
  
  ------------------------------------------
  
  Hope you find the answer to this, as whilst it does not adversely affect the running application it is clearly a serious problem within the heart of the .NET 2.0 Framework.
  
  Regards
  Paul
  

• Anonymous
  April 21, 2006
  David,
  
  Sorry, re the above entry from Paul:
  
  The reason the Process Up time is only around 8 mins is because I was using different timeouts for the app pool recycling to ensure it was actually this that was causing it.
  
  If I set to 5 mins the error occurs 5 mins after last page hit, if to 10 mins, then crash occurs 10 mins after last page hit. etc etc.
  
  This one was set to 5 mins and I last used the page about 3 mins into app pool threads lifespan.
  
  Hope this helps narrow it down
  
  Regards
  Paul
  

• Anonymous
  April 24, 2006
  David, The answer
  
  The crashes are occurring because of permissions being reset on the following key.
  
  HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesASP.NET_2.0.50727Names.
  
  The ASPNET 2.0 install routine sets this key up correctly, otherwise you would expect to see an error thrown at install tiem but then on some computers the ACLs are overridden by either GPO/Local Security Policy or some other mechanism. This is why it is random or appears to be. And probably why people are finding it so hard to track down.
  
  I set ACLs for ASPNET and Network Service on this key on Friday and all worked well, the crashes were no more. Then  this morning, the crashes were back, I checked the Reg Key and the ACLs had been reset to default.
  
  Am currently investigating what is causing this, it does not appear to be GPO.
  
  Hope this helps.
  Regards
  Paul
  
  
  
  

• Anonymous
  April 27, 2006
  Hi Paul
  
  NETWORK SERVICE not having access to that reg key is definitely one cause of this crash as I commented on the 12th April. We have a KB artticle in progress about this. Normally NETWORK SERVICE has these permissions by virtue of being in the IIS_WPG local group. The only confirmed scenario we have so far where this problem arises is when the server is upgraded to a domain controller and the IIS_WPG group gets upgraded to a domain group (as there are no local groups on a domain controller).  NETWORK SERVICE is not able to be in a domain group as it is a BUILTIN account.
  
  So if you do figure out why the permissions got changed in your case that would be useful to know.
  
  Regards
  
  Doug

• Anonymous
  April 28, 2006
  Many thanks for the response.
  
  I have narrowed this down a lot more now. And it was GPO! But a setting not defined in the .inf file I configured them with so could be someone was having a play in AD. Here is my solution.
  
  I thought at first I had cracked it with aspnet_regiis -i but then a day later the errors were back.
  
  Checked GPOs and the GPO registry setting on Key MACHINESystem was set to replace any lower ACLs, thus when GPO was pushed, all ACLs where removed from key except those defined in base GPO.
  
  Reset GPO to inherit to lower keys not replace, reset ACLs on names key, ran gpupdate /force, ran IISRESET just for good measure.
  
  BINGO, all still working 5 days later.
  
  Obviously one could set an GPO entry for that specific key and get the same result as long as applied after the MACHINESystem entry. I have other keys in the GPOs that set themselves after the MACHINESystem entry is run, so will look at that next week.
  
  This was a hard one to track down, as there seems to be no link to GPO at first and you look to other avenues. You assume that .NET 1.1 worked under same GPOs so why not this?
  
  Anyway, I am a happy bunny today
  Regards
  Paul
  

• Anonymous
  April 28, 2006
  Actually, if anyone knows if this is a default setting on the following key.
  
  HKEY_LOCAL_MACHINESYSTEM
  
  Configure this key then
  Replace existing permissions on all subkeys with inhertiable permissions.
  
  In order to fix this I have changed this to
  Configure this key then
  Propagate inheritable permissions to all subkeys
  
  And all works well.
  
  Just wondered, as this might cause issues as some of the apps I host are moving into other domains.
  
  Regards
  Paul
  

• Anonymous
  April 28, 2006
  Paul - glad that you got to the bottom of this.
  
  Now, you do illustrate the point that once a machine joins a domain or becomes a domain controller, GPO and such "automatic" reconfigurations of the machine can be pretty deadly against IIS. Most of the time that I have seen "bizarre" IIS errors/behaviors, they have all come from GPO doing arbitrary "Lockdown" of the machine that ended up breaking IIS in random ways.
  
  I believe it is not because IIS6 has a lot of dependencies, but rather because most GPO expect a CLIENT usage experience and IIS clearly requires a SERVER usage experience. A lot of the GPOs would lock down the machine assuming servers/services are bad... and then the guy needs to develop against a personal IIS server which basically goes against the GPO's intent. The resulting breakage makes IIS look bad when in fact the user is broken relative to their GPO. But try telling that to the user! ;-)
  
  //David

• Anonymous
  May 03, 2006
  I want to thank dougste for his solution, it solved the problem. Thank you very much.

• Anonymous
  May 15, 2006
  Microsoft PSS fixed our issue using the following kb article:
  
  http://support.microsoft.com/kb/918041/en-us

• Anonymous
  May 19, 2006
  I'm getting WebDev.WebServer.exe crashing all the time at the moment, despite having done a Detect and Repair with Visual Studio 2005, but I guess that's not so helpful to you?
  
  Unfortunately, I'm not sure what actually caused the problem but, for the last couple of days (and without having installed anything or changed any registry settings between it working and it not working) every time I try to View in Browser a page in my web project, it launches the Cassini-based server engine, then crashes.
  
  If it helps, the information displayed in the short form of the error report is:
  
  AppName: webdev.webserver.exe
  AppVer: 8.0.50727.42
  AppStamp: 4333d6f1
  ModName: kernel32.dll
  ModVer: 5.1.2600.2180
  ModStamp: 411096b4
  fDebug: 0
  Offset: 001eb33
  
  I had a look at Q918041, as one of these comments suggested, but I don't have an IIS_WPG group on my machine. I set the Network Service account to have the same privileges on that registry key as the ASPNET account has, but that doesn't seem to have resolved it.
  
  If you need to contact me further, I'm owenblacker (at) uswitch (dot) com; feel free to email me.

• Anonymous
  May 19, 2006
  A little more information.
  
  Most (not all) instances of this problem have two items in the event log (two only have the Error and not the Information):
  
  Error:
  
  Source: .Net Runtime 2.0 Error
  Category: None
  Event ID: 1000
  Description: Faulting application webdev.webserver.exe, version 8.0.50727.42, stamp 4333d6f1, faulting module kernel32.dll, version 5.1.2600.2180, stamp 411096b4, debug? 0, fault address 0x0001eb33.
  
  Information (up to three minutes later and potentially unrelated):
  
  Source: .Net Runtime 2.0 Error
  Category: None
  Event ID: 1001
  Description: Bucket 235550748, bucket table 1, faulting application webdev.webserver.exe, version 8.0.50727.42, stamp 4333d6f1, faulting module kernel32.dll, version 5.1.2600.2180, stamp 411096b4, debug? 0, fault address 0x0001eb33.

• Anonymous
  June 08, 2006
  Owen Blacker - you are seeing a crash in the Cassini-based webserver. This actually has nothing to do with IIS because you are talking about two completely different code-bases.
  
  Thus, the best way to troubleshoot is to simply attach a debugger onto the webdev.webserver.exe process, trigger the crash, and debug the assembly code. I suspect you are somehow causing ASP.Net to load some HttpModule or HttpHandler that crashes, or maybe ASP.Net is having problems compiling due to changed user permissions. No idea. You need to capture the crash and debug it to figure it out.
  
  So really, this issue has nothing to do with IIS and is in the realm of general debugging...
  
  //David

• Anonymous
  August 01, 2006
  I'm having it crash as well. DEP also shows up showing something naughty happened. Something of interest, our websites function -- but function slowly after a crash. Here is some detailed info...
  
  
  Faulting application w3wp.exe, version 6.0.3790.1830, stamp 42435be1, faulting module webengine.dll, version 2.0.50727.42, stamp 4333eca4, debug? 0, fault address 0x00002fec.
  
  For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
  
  
  

• Anonymous
  August 01, 2006
  Kenny - a stack trace is necessary for diagnosis. It seems like one of the known failure patterns so you can search for a KB or contact Microsoft PSS for support.
  
  //David

• Anonymous
  August 16, 2006
  Try this :
  http://support.microsoft.com/default.aspx?scid=kb;en-us;911816

• Anonymous
  September 25, 2006
  this will generate the exception:
  
  System.Web.Security.FormsAuthenticationTicket t = new System.Web.Security.FormsAuthenticationTicket(txtUser.Text, true, int.MaxValue);
             string usr = System.Web.Security.FormsAuthentication.Encrypt(t);

• Anonymous
  May 19, 2007
  WebEngine crash with following error: Faulting application w3wp.exe, version 6.0.3790.3959, stamp 45d6968e, faulting module webengine.dll, version 2.0.50727.210, stamp 45072279, debug? 0, fault address 0x00002fe7. W2K3 R2 SP2 SQL 2005 and 2005 Reporting Services with SP1. Production goes down once a day. HELP :)

• Anonymous
  May 24, 2007
  3-4 crashes a day when running on Server 2003 SP1 - Sharepoint Services 3.0 w3wp.exe 6.0.3790.1830 webengine.dll 2.0.50721.210 00002fe7

• Anonymous
  May 28, 2007
  Still have Webengine.dll crash - interesting is that there is no rule how and when it will crash (at least I can't point it out...) Whole event log (app, system) is blue except this little warning (not error) about asp.net 2.0 web event - which normaly you can misjudge as a minor event. I have problems also on W2K3 SP2/SQL2K5 SP2 platform, so it's not related to hotfixes or SPs - I guess. Also I checked all security permissions for acccounts - from dir to registry - still nothing. any help appreciated

• Anonymous
  May 30, 2007
  I've been running into the same crashes and it all seemed to start when I installed Sharepoint services 3.0. An unistall or a reinstall does not fix the crashes. Argggg. Faulting application w3wp.exe, version 6.0.3790.3959, faulting module webengine.dll, version 2.0.50727.42, fault address 0x00002fec.

• Anonymous
  June 24, 2007
  Have a try at the following hotfix. It did the work for me. http://support.microsoft.com/default.aspx/kb/934839

• Anonymous
  August 21, 2007
  with WSUS 3.0 this occurrs at one of my clients. without WSUS 3 then no problems

• Anonymous
  October 16, 2007
  The comment has been removed

• Anonymous
  October 16, 2007
  The comment has been removed

• Anonymous
  October 16, 2007
  Ok, it looks like the WWW Publishing service is stopping.  Any ideas?

• Anonymous
  February 08, 2008
  WebEngine.dll has been the source of unhandled exceptions when viewing aspx pages for the last couple of days which would stop IIS. Am using VS2005 on XP SP2 with IIS 5.1 . I have used DebugDiag to capture full dumps if they are of interest ? The exceptions appeared to be occurring after the Page_Unload event so some issue with Unloading the pages. The logs backed this up as Page_Unload events were written prior to the exception. I have reinstalled IIS, reregistered .NET v2.0.50727 with IIS and it seems to have cleared it up. If I have the time I might reinstate an IIS configuration that was backed up prior to reinstalling and see if the errors return.

• Anonymous
  February 29, 2008
  Hi. i had some project in .net 2005 (Asp.net) and Now i install .net 2008. when i open my website with .net 2005 (I have .net 2005 and 2008 in my system together) 1 error occured : " unable to load webengine.dll". and what's your solution to open my 2005 project in VS.net2005. thank you karwan

• Anonymous
  July 29, 2008
  Running: WinXP w/ SP2, ASP.Net 2.0 and Ajax 1.0 After recent MS security updates to my development machine (pushed by my IS department, may be coincidental), I have begun getting crashes in inetinfo.exe / webengine.dll; Unhandled exception at 0x6a2aca76 in inetinfo.exe: 0xC0000005: Access violation reading location 0x00000004. Top of Call Stack: webengine!AspNetGetExtensionVersion+0xbcc This happens with all my web applications, even a very simple test application I created. I have created dumps using DRWTSN32 and ADPlus, both show the same information. Trapping it in VS2005 debugger also shows the same stack. None of these shed any light on the root cause or possible fixes. Here is a bit from the dretsn32.log; ----> State Dump for Thread Id 0x44c <---- eax=00000000 ebx=00000000 ecx=01212a54 edx=01212a54 esi=00000001 edi=00000068 eip=6a2aca76 esp=0159f284 ebp=00000000 iopl=0         nv up ei pl nz na pe nc cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000202 function: webengine!AspNetGetExtensionVersion        6a2aca44 0cf3             or      al,0xf3        6a2aca46 2d6ae8680b       sub     eax,0xb68e86a        6a2aca4b 0000             add     [eax],al        6a2aca4d 8be8             mov     ebp,eax        6a2aca4f 3beb             cmp     ebp,ebx        6a2aca51 7540        jnz webengine!AspNetGetExtensionVersion+0xbe9 (6a2aca93)        6a2aca53 a110f32d6a       mov     eax,[webengine+0x3f310 (6a2df310)]        6a2aca58 56               push    esi        6a2aca59 33f6             xor     esi,esi        6a2aca5b 395804           cmp     [eax+0x4],ebx        6a2aca5e 7e1c        jle webengine!AspNetGetExtensionVersion+0xbd2 (6a2aca7c)        6a2aca60 57               push    edi        6a2aca61 33ff             xor     edi,edi        6a2aca63 8b08             mov     ecx,[eax]        6a2aca65 53               push    ebx        6a2aca66 03cf             add     ecx,edi        6a2aca68 e819ffffff call webengine!AspNetGetExtensionVersion+0xadc (6a2ac986)        6a2aca6d a110f32d6a       mov     eax,[webengine+0x3f310 (6a2df310)]        6a2aca72 46               inc     esi        6a2aca73 83c768           add     edi,0x68 FAULT ->6a2aca76 3b7004           cmp     esi,[eax+0x4]     ds:0023:00000004=????????        6a2aca79 7ce8         jl webengine!AspNetGetExtensionVersion+0xbb9 (6a2aca63)        6a2aca7b 5f               pop     edi        6a2aca7c 53               push    ebx        6a2aca7d 53               push    ebx        6a2aca7e 6814132a6a       push    0x6a2a1314        6a2aca83 891d00f32d6a     mov     [webengine+0x3f300 (6a2df300)],ebx        6a2aca89 ff152c122a6a     call    dword ptr [webengine+0x122c (6a2a122c)]        6a2aca8f 83c40c           add     esp,0xc        6a2aca92 5e               pop     esi        6a2aca93 8bc5             mov     eax,ebp        6a2aca95 5d               pop     ebp        6a2aca96 5b               pop     ebx        6a2aca97 c3               ret        6a2aca98 6a01             push    0x1        6a2aca9a e80e380000  call webengine!LoadLibraryUsingFullPath+0x243 (6a2b02ad)        6a2aca9f 833d54f52d6a00   cmp    dword ptr [webengine+0x3f554 (6a2df554)],0x0        6a2acaa6 7412         jz webengine!AspNetGetExtensionVersion+0xc10 (6a2acaba)        6a2acaa8 e83e2e0000       call    webengine!GetXSPInstance+0x502 (6a2af8eb)        6a2acaad e88cffffff call webengine!AspNetGetExtensionVersion+0xb94 (6a2aca3e)        6a2acab2 85c0             test    eax,eax Security updates installed just prior to the events; http://support.microsoft.com/?kbid=935843 http://support.microsoft.com/?kbid=935839 http://support.microsoft.com/?kbid=935840 http://support.microsoft.com/?kbid=929123 http://support.microsoft.com/?kbid=933566 I can upload/email any logs/dmp files if needed. Any help would be greatly appreciated... Thanks in advance.

• Anonymous
  August 02, 2008
  Todd - I recommend contacting Microsoft PSS and open a support case with them so that they can debug your issue. This looks like a crash within WebEngine.dll which is loaded within inetinfo.exe by aspnet_isapi.dll, all of which is in Microsoft code. As a reminder -- this is how one DETERMINES the root cause of any crash:

1. A tool to capture the exception of interest
2. A debugger to interact with the crash memory dump, with symbols
3. A human with knowledge of how to read the memory dump You have only used tools to do #1. You have not done #2 nor #3, so your expectations of determining the root cause will not be fulfilled. At this point in time, there is no tool that can perform #3 generically. When we have such a tool, humans will no longer need to write software because software can author and debug itself... //David

• Anonymous
  August 30, 2009
  while working after Tc internet cannot brouse & dll crash

• Anonymous
  September 02, 2009
  I cannot definitively state what caused it in my case.  I was in the middle of compiling a web site when it first occurred.  AFAIK, nothing was installed or updated at the time or before that point during the day.  The event log contains no indications of problem prior to the first failed load. With help from this site I eventually discovered the WWW Publishing Service was shut down and changed to manual mode, so it was not restarting when I rebooted.  Restarting the service resolved the problem for me.

• Anonymous
  November 04, 2009
  I just spent a day on this problem tracking down the same error, Unable to load webengine.dll. In both Cassini and aspNetServe. Both cases the exception was thrown from ApplicationManager.CreateObject(...). It worked on my desktop but not my development laptop. In my case it was a supid error, I had the path to the web directory in the app.config but the directory was on a different drive so the path was wrong. It seems the error "Unable to load webengine.dll, dll not found" has nothing to do with the actual problem.

• Anonymous
  July 16, 2011
  The problem occurs when trying to embed the Cassini Web Server in a dotNet application/solution using VS2010 Pro. After starting Cassini, then trying to access the page results in the webengine exception. Though VS2010 Pro comes with a development ASP.Net Server, suspect that have to investigate/change the version of Cassini???