Error trying to start Silverlight Business Application

I am aloof from this error. I can’t understand in my life what the problem is. Even when I deleted all the changes I made in order to return to the base application that was created when I created it, it still has the same error. Once I managed to figure it out, but I don’t know what I did to get it.

If someone can help me understand this error, I would be very grateful!

I can't even debug a breakpoint, because it does not even reach any of the breakpoints that I set. The message is as follows:

Error
Exception has been thrown by the target of an invocation.

Error Details
   at System.Windows.Navigation.PageResourceContentLoader.EndLoad(IAsyncResult asyncResult)
   at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)
Caused by: Exception has been thrown by the target of an invocation.

   at System.Windows.Navigation.PageResourceContentLoader.EndLoad(IAsyncResult asyncResult)
   at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)
Caused by: Exception has been thrown by the target of an invocation.

   at System.Windows.Navigation.PageResourceContentLoader.EndLoad(IAsyncResult asyncResult)
   at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)

Has anyone else come across this? Does anyone know how to fix this so that I can continue to work on the same project after throwing it?

thank