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FIX: You may receive an InvalidCastException error in an ASP.NET-connected Web application

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Article ID:915782
Last Review:December 3, 2007
Revision:3.2

SYMPTOMS

You may receive an InvalidCastException error in a Microsoft ASP.NET-connected Web application when the following conditions are true:
•The Web application uses a master page, a user control, or pages that reference each other.
•The master page, the user control, or the pages are batch compiled into a single assembly.
•One of the batched dependencies is changed and causes a recompilation.
•A dynamic call to load a reference is made, such as a call to the LoadControl method.
In this case, you may receive an error message that resembles the following:
Unable to cast object of type 'ASP.type' to type 'ASP.type'.
Note In this error message, type is a placeholder for one of the batch compiled types.

You may also receive an error message that resembles the following:
Could not load file or assembly 'App_Web_xxxxxxxx, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

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RESOLUTION

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only 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, visit the following Microsoft Web site:
http://connect.microsoft.com/VisualStudio/content/content.aspx?ContentID=3705 (http://connect.microsoft.com/VisualStudio/content/content.aspx?ContentID=3705)
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.
File nameFile versionFile sizeDateTime
Aspnet_wp.exe2.0.50727.8023,04028-Feb-200612:06
System.web.dll2.0.50727.805,025,79228-Feb-200612:06
Webengine.dll2.0.50727.80299,52028-Feb-200612:06

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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

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
824684 (http://support.microsoft.com/kb/824684/) Description of the standard terminology that is used to describe Microsoft software updates
919284 (http://support.microsoft.com/kb/919284/) Error messages when you try to run an ASP.NET 2.0 Web application that is built on the .NET Framework 2.0
934839 (http://support.microsoft.com/kb/934839/) FIX: You may receive an exception when you browse a .NET Framework 2.0 ASP.NET Web application

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APPLIES TO
•Microsoft .NET Framework 2.0

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Keywords: 
kbbug kbfix kbqfe kbpubtypekc kbhotfixserver KB915782

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