Sunday, May 30, 2010

[Tutorial] Migration to Framework .NET 4.0 & Visual Studio 2010
Part3: Migration Issues and their Solutions

The last part of the series showed the Visual Studio 2010 Conversion Wizard. This part explains what needs to be done in case of migration issues.

Most of the changes in .NET 4.0 do not require any code modifications. But sometimes you will encounter problems and that is where you will need to apply some workaround solutions. I am going to show you some examples of these solutions in this article.


Access to configuration files was modified. If your configuration file is named “MyApplication.config” you will have to rename it to “MyApplication.exe.config”.


When using the Conversion Wizard within Visual Studio 2010 to convert your ASP.NET 3.5 applications to ASP.NET 4.0, the Web.config file is also modified in the process. It contains new parameters that might not be exactly configured as you like it.

  • The display mode of some controls was modified. To deactivate this new display mode change the following parameter:
    <pages controlRenderingCompatibilityVersion="3.5" />

  • The validation mode of HTTP requests was ameliorated (cross-site scripting protection). To reestablish the preceding behavior add the following parameter:
    <httpRuntime requestValidationMode="2.0" />

  • The UrlEncode and HtmlEncode methods were modified. Please verify that they work as expected.

  • The page parser for ASPX and ASCX is stricter than before. You should fix any invalid markup.

Windows Presentation Foundation (WPF)

The XAML parsing was modified. XAML attributes cannot contain more than one period anymore.

The following are valid examples after the migration:
<button Background="Red"/>
<button Button.Background="Red"/>

The following is not accepted anymore after the migration:
<button Control.Button.Background="Red"/>

Additional Information in MSDN

For further information on this subject and much more workaround solutions, please visit Microsofts MSDN site:


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