FIX: An HttpAsyncResult handler may be released two times and cause an unhandled NullReferenceException exception in the HandlerFactoryWrapper.ReleaseHandler method in ASP.NET 2.0

View products that this article applies to.

Symptoms

In ASP.NET 2.0, an HttpAsyncResult handler may be released two times under certain circumstances. This causes an unhandled NullReferenceException exception in the System.Web.Configuration.HandlerFactoryWrapper.ReleaseHandler method. In addition, the process may crash because of the unhandled NullReferenceException exception.

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Resolution

Service Pack Information

To resolve this problem, obtain the .NET Framework 3.5 Service Pack 1 (SP1). To obtain the .NET Framework 3.5 SP1, visit the following Microsoft Web site:

http://www.microsoft.com/downloads/details.aspx?familyid=ab99342f-5d1a-413d-8319-81da479ab0d7&displaylang=en

Hotfix Information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

There are no prerequisites.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

x86

Collapse this tableExpand this table

File name	File version	File size	Date	Time
Aspnet_perf.dll	2.0.50727.1856	31,056	17-Oct-2008	11:28
aspnet_perf.h	Not Applicable	6,537	17-Oct-2008	11:28
aspnet_perf.ini	Not Applicable	895,678	17-Oct-2008	11:28
aspnet_state_perf.h	Not Applicable	318	17-Oct-2008	11:28
aspnet_wp.exe	2.0.50727.1856	31,048	17-Oct-2008	11:28
webengine.dll	2.0.50727.1856	431,432	17-Oct-2008	11:28
System.Web.dll	2.0.50727.1856	5,185,536	17-Oct-2008	11:28

x64

Collapse this tableExpand this table

File name	File version	File size	Date	Time
Aspnet_perf.dll	2.0.50727.1856	38,736	17-Oct-2008	08:26
Aspnet_perf.dll	2.0.50727.1856	31,056	17-Oct-2008	11:28
aspnet_perf.h	Not Applicable	6,537	17-Oct-2008	05:01
aspnet_perf.h	Not Applicable	6,537	17-Oct-2008	11:28
aspnet_perf.ini	Not Applicable	897,682	17-Oct-2008	05:07
aspnet_perf.ini	Not Applicable	897,676	17-Oct-2008	11:28
aspnet_perf2.ini	Not Applicable	895,684	17-Oct-2008	05:07
aspnet_perf2.ini	Not Applicable	895,678	17-Oct-2008	11:28
aspnet_state_perf.h	Not Applicable	318	17-Oct-2008	05:01
aspnet_state_perf.h	Not Applicable	318	17-Oct-2008	11:28
aspnet_wp.exe	2.0.50727.1856	42,824	17-Oct-2008	08:26
aspnet_wp.exe	2.0.50727.1856	31,048	17-Oct-2008	11:28
webengine.dll	2.0.50727.1856	735,560	17-Oct-2008	08:26
webengine.dll	2.0.50727.1856	431,432	17-Oct-2008	11:28
System.Web.dll	2.0.50727.1856	5,263,360	17-Oct-2008	08:26
System.Web.dll	2.0.50727.1856	5,185,536	17-Oct-2008	11:28

IA64

Collapse this tableExpand this table

File name	File version	File size	Date	Time
Aspnet_perf.dll	2.0.50727.1856	80,720	17-Oct-2008	09:06
Aspnet_perf.dll	2.0.50727.1856	31,056	17-Oct-2008	11:28
aspnet_perf.h	Not Applicable	6,537	17-Oct-2008	04:54
aspnet_perf.h	Not Applicable	6,537	17-Oct-2008	11:28
aspnet_perf.ini	Not Applicable	897,682	17-Oct-2008	05:00
aspnet_perf.ini	Not Applicable	897,676	17-Oct-2008	11:28
aspnet_perf2.ini	Not Applicable	895,684	17-Oct-2008	05:00
aspnet_perf2.ini	Not Applicable	895,678	17-Oct-2008	11:28
aspnet_state_perf.h	Not Applicable	318	17-Oct-2008	04:54
aspnet_state_perf.h	Not Applicable	318	17-Oct-2008	11:28
aspnet_wp.exe	2.0.50727.1856	81,736	17-Oct-2008	09:06
aspnet_wp.exe	2.0.50727.1856	31,048	17-Oct-2008	11:28
webengine.dll	2.0.50727.1856	1,211,720	17-Oct-2008	09:06
webengine.dll	2.0.50727.1856	431,432	17-Oct-2008	11:28
System.Web.dll	2.0.50727.1856	4,743,168	17-Oct-2008	09:06
System.Web.dll	2.0.50727.1856	5,185,536	17-Oct-2008	11:28

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Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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More information

Call stack output

The exception call stack resembles the following:

Exception object: 0000000080be7a10
Exception type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
InnerException: <none>
StackTrace (generated):
    SP               IP               Function
    0000000012DEE550 00000642BC9F7076 System.Web.Configuration.HandlerFactoryWrapper.ReleaseHandler(System.Web.IHttpHandler)
    0000000012DEE580 00000642BCB26156 System.Web.HttpApplication.RecycleHandlers()
    0000000012DEE5D0 00000642BCB2625F System.Web.HttpApplication.ReleaseAppInstance()
    0000000012DEE600 00000642BCB2365F System.Web.HttpApplication+ApplicationStepManager.ResumeSteps(System.Exception)
    0000000012DEE6B0 00000642BCB277F5 System.Web.HttpApplication.ResumeStepsFromThreadPoolThread(System.Exception)
    0000000012DEE6F0 00000642BCB248C7 System.Web.HttpApplication+AsyncEventExecutionStep.ResumeStepsWithAssert(System.Exception)
    0000000012DEE750 00000642BCB249DD System.Web.HttpApplication+AsyncEventExecutionStep.OnAsyncEventCompletion(System.IAsyncResult)
    0000000012DEE7D0 00000642BCB20775 System.Web.HttpAsyncResult.Complete(Boolean, System.Object, System.Exception, System.Web.RequestNotificationStatus)
    0000000012DEE810 00000642BC935F41 System.Web.SessionState.SessionStateModule.PollLockedSessionCallback(System.Object)

This may also be followed by another exception:

Exception object: 0000000080be7c30
Exception type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
InnerException: <none>
StackTrace (generated):
    SP               IP               Function
    0000000012DEC360 00000642BCD4EC3C System.Web.SessionState.SessionStateModule.PollLockedSessionCallback(System.Object)
    0000000012DEE8B0 00000642780A9BC3 System.Threading.ExecutionContext.runTryCode(System.Object)
    0000000012DEF120 0000000000000001 System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode, CleanupCode, System.Object)
    0000000012DEF120 00000642780A9727 System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
    0000000012DEF170 0000064278338D07 System.Threading._TimerCallback.PerformTimerCallback(System.Object)

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