You have a Windows Presentation Foundation (WPF) XAML browser application (XBAP). When you run the application in Mozilla Firefox 3.0 (or later versions), the application crashes or the Web browser crashes. When you debug the application, you receive a System.ComponentModel.Win32Exception exception. Additionally, you receive the following error message:

Unknown error (0x105)
at MS.Internal.AppModel.CookieHandler.SetCookieUnsafe(Uri uri, String cookieData, String p3pHeader)
at MS.Internal.AppModel.CookieHandler.SetCookie(Uri uri, String cookieData)
at System.Windows.Application.SetCookie(Uri uri, String value)


This problem occurs because the identity of an interface that is used by the WPF Firefox plug-in (Npwpf.dll) to manipulate cookies has changed in Mozilla Firefox 3.0 (or later versions) of Firefox. Therefore, a NULL cookie service reference is returned to the plug-in. When the plug-in tries to use the cookie service, an access violation occurs.

Note The Npwpf.dll plug-in is a part of the Microsoft .NET Framework 3.5 or the .NET Framework 3.5 Service Pack 1 (SP1).


Hotfix information

To obtain this hotfix, use one of the following methods.

Method 1

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 this specific problem. 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.

To download this hotfix from the MSDN Code Gallery, visit the following Microsoft Web site:
Note The MSDN Code Gallery displays the languages for which the hotfix is available. If you do not see your language listed, it is because the Code Gallery resource page is not available for that language.

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:

Method 2

The following file is available for download from the Microsoft Download Center:
Download Download the NDP35SP1-KB969140-x64.exe package or the NDP35SP1-KB969140-x86.exe package now.

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to obtain Microsoft support files from online services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.


You must have the .NET Framework 3.5 SP1 installed to apply this hotfix.

Restart requirement

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

Hotfix replacement information

This hotfix replaces the hotfix that is described in the following Microsoft Knowledge Base (KB) article:

971643 FIX: You receive a "System.ComponentModel.Win32Exception" exception when you run a WPF Browser application to read or write a cookie in a Firefox Web browser

File information

The global 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.

File name

File version

File size










The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.


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 about software update terminology, 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

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