Category Archives: WPF

The project file contains a property value that is not valid – WPF error


While developing a WPF application I had created a new project in my solution. I then copied several pages from one project to the new project. On running the application I got the wierd error “The project file contains a property value that is not valid”. I checked the files and codebehind over and over without finding the problem.






Eventually the problem turned out to be the build action for the pages that I had copied! aaargh. They had been set to “ApplicationDefinition”, setting them back to “Page” solved the problem. Other files like images etc show similar issues so be aware of this!!



PRISM application

I’ve been tasked with building a simple proof of concept application by next week. It MUST be modular and loosely coupled. It SHOULD be portable to Silverlight and possibly mobile applications. Not actually having built a WPF application yet this has me excited. As a bonus I get to implement PRISM and the MVVM pattern plus choose a dependacy injection container.

Once the proof of concept succeeds this most likely be the basis of a complete overhaul of the existing systems we are working with! Wish me luck! 🙂

Update -Right now I’m feeling a bit overwhelmed. After reading some of a ‘Developer’s Guide to Microsoft Prism’ yesterday I had the impression I had a choice between 2 depedancy injection containers MEF or Unity (yes there are others but these 2 are for now the most logical choice).

After reading David Hill’s blog ( it seems it can be argued that MEF isn’t even a DI container. In fact MEF and Unity can be used together with PRISM! Obviously I can’t expect to learn these concepts within a week.