Microsoft KB Archive/945756

= Error message when you compile a WPF application in Visual Basic 2008: &quot;Option Strict On disallows implicit conversions&quot; =

Article ID: 945756

Article Last Modified on 12/3/2007

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APPLIES TO


 * Microsoft Visual Studio 2008 Standard Edition
 * Microsoft Visual Studio 2008 Professional Edition
 * Microsoft Visual Studio 2008 Team Edition for Database Professionals
 * Microsoft Visual Studio 2008 Team Edition for Software Architects
 * Microsoft Visual Studio 2008 Team Edition for Software Developers
 * Microsoft Visual Studio 2008 Team Edition for Software Testers
 * Microsoft Visual Studio 2008 Team Suite
 * Microsoft Visual Basic 2008 Express Edition

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SYMPTOMS
You may receive an error message that resembles the following when you try to compile a Windows Presentation Foundation (WPF) application in Microsoft Visual Basic 2008:

Option Strict On disallows implicit conversions from 'System.Windows.Application' to 'WpfApplication1.Application'.



CAUSE
This issue occurs if the value of the Option Strict statement is &quot;On&quot; at the project level.



RESOLUTION
To resolve this issue, download an updated WPF template. To obtain the updated template, visit the following Microsoft Web site:

http://go.microsoft.com/fwlink/?LinkId=105130

Important You do not have to unzip the compressed file with a .zip file name extension to install the updated template. To install the updated template, put the .compressed file with a .zip file name extension in the \Visual Studio 2008\Templates\ProjectTemplates\Visual Basic folder, and then restart Visual Studio 2008.

After you install the updated template, the updated template appears in the New Project dialog box in the My Templates section. This section is located under the Visual Studio installed templates section.



WORKAROUND
To work around this issue in the current project, modify the code in the Mywpfextension.vb file. To modify the code in the Mywpfextension.vb file, follow these steps:  Under Error List, double-click the error message that the &quot;Symptoms&quot; section describes. The Mywpfextension.vb file opens.  Locate the following line of code: Return Global.System.Windows.Application.Current   Modify the code in step 2 as follows: Return CType(Global.System.Windows.Application.Current, Application)  Build the project again.



MORE INFORMATION
This issue occurs because the code in the WPF template performs an implicit cast. Implicit casts are not allowed when Option Strict checking is turned on.

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