创建新的SL4导航应用时出现编译错误

Question

I created a new Silverlight Navigation Application using Visual Studio 2010. I didn't make any changes to the code. Just Pressed F5 to run. I get the following error message:

The type 'System.Windows.Navigation.NavigationEventArgs' exists in both 'c:\\Program Files (x86)\\Reference Assemblies\\Microsoft\\Framework\\Silverlight\\v4.0\\System.Windows.Controls.Navigation.dll' and 'c:\\Program Files (x86)\\Reference Assemblies\\Microsoft\\Framework\\Silverlight\\v4.0\\System.Windows.dll'

I right clicked the Silverlight Navigation Application folder in the solution explorer and changed its "Target Silverlight Version" from Silverlight 4 to Silverlight 3 and then ran the application (by pressing F5) and it works fine.

I've already spent a lot of time trying to fine a solution. I want to develop application using Silverlight 4.

Would really appreciate any help with this.

Regards, Vivek

Answer 1

It sounds like you have Silverlight 4's runtime, but an older set of VS tools or an older SDK, or your project is somehow referencing the older SDK.

Basically, that type moved from the System.Windows.Controls.Navigation DLL (where it was in SL3) to System.Windows.dll (where it is in SL4). CLR type-forwarding should take care of this.

Since Silverlight version numbers on assemblies didn't change between SL3 and SL4 it can be somewhat hard to tell if you're in the situation where you have outdated tools/SDK. Check the last modified date on System.Windows.Controls.Navigation.dll and see if it looks like about the time SL4 was released, or check if the Frame control has a property called ContentLoader - if so, you have the updated bits (and my answer is thus not helping). If not, however, then try reinstalling the SL4 Tools and/or SDK and check that your project is referencing the v4 Navigation assembly.