FIX: ASP.NET 2.0-connected applications on a Web site may appear to stop responding

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Article ID: 911272 - View products that this article applies to.
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Symptoms

Consider the following scenario:
  • You browse a Microsoft ASP.NET 2.0-based Web site or a Web site that is running an ASP.NET 2.0-connected application.
  • The Web site has thousands of subdirectories.
In this scenario, the ASP.NET 2.0-connected application or the ASP.NET 2.0-based Web site may appear to stop responding.

Cause

This problem occurs because ASP.NET 2.0 sets up a file change notification for each directory. As the number of subdirectories increases, the numbers of file change notifications grows. Each file change notification uses a Server Message Block (SMB) command. Because SMB commands use system resources, the increased usage of system resources makes the ASP.NET-based Web site or the ASP.NET-connected application appear to stop responding.

Resolution

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft .NET Framework 2.0 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=support
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

The .NET Framework 2.0

Restart requirement

You must restart the computer if any ASP.NET or .NET Framework applications are running.

Hotfix replacement information

This hotfix does not replace any other software updates.

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 tool in Control Panel.
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File nameFile versionFile sizeDateTimePlatform
Aspnet_wp.exe2.0.50727.6223,04021-Jan-200612:08x86
System.web.dll2.0.50727.625,025,79221-Jan-200612:09x86
Webengine.dll2.0.50727.62299,52021-Jan-200612:08x86

Registry information

To enable this hotfix, you must add the following DWORD value at the following registry key:
HKLM\Software\Microsoft\ASP.NET\FCNMode

If you are running a 32-bit process on an x64-based system, add the following DWORD value at the following registry key:
HKLM\SOFTWARE\Wow6432Node\Microsoft\ASP.NET\FCNMode
The following table lists possible values for the FCNMode DWORD value and the behavior that is associated with each value.
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ValueBehavior
Does not exist This is the default behavior. For each subdirectory, the application will create an object that will monitor the subdirectory.
0 or greater than 2This is the default behavior. For each subdirectory, the application will create an object that will monitor the subdirectory.
1The application will disable File Change Notifications (FCNs).
2The application will create one object to monitor the main directory. The application will use this object to monitor each subdirectory.

Note Starting with the Microsoft .NET Framework 4.5 and later versions, FCNMode can be configured by using the httpRuntime settings as follows:
<httpRuntime fcnMode="<setting>"/>
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SettingCorresponding value
NotSet(0)This is the same as setting 0 or greater than 2 in the registry.
Default (1)This is the same as setting 0 or greater than 2 in the registry.
Disabled (2)This is the same as setting 1 in the registry.
Single (3)This is the same as setting 2 in the registry.
For example, you can use httpRuntime as follows to disable FCNMode:
<httpRuntime fcnMode="Disabled"/> 

Status

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

More information

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates

Properties

Article ID: 911272 - Last Review: May 7, 2014 - Revision: 4.0
Applies to
  • Microsoft .NET Framework 2.0
Keywords: 
kbHotfixServer kbfix kbbug KB911272

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