I created a Visual Studio 2013 Lightswitch Desktop solution. I copied it from one machine to another and it worked fine on both, but another developer could not open it on his machine. To the right of each project in the solution appeared “(Incompatible)”.
We created a new Lightswitch project using VS2013 on his computer. No problem. It opened fine.
Looking at the project files with a text editor we noticed that the LightswitchVersion XML element was 4.0, where the same element in the project I created was 4.5. We had the same version of Visual Studio (VS2013 Professional, Update 1), and the same versions of the .Net Framework and Silverlight. In fact my development workstation (a virtual machine) had originally been cloned from his!
Finally we noticed that I had installed the “Microsoft Office Developer Tools for Visual Studio 2013 – March 2014 Update” and he had not. We installed this on his machine and were immediately able to open all the projects previously labeled “(Incompatible)”. These developer tools allow the development of “Cloud Business Apps” using Lightswitch, a new feature, although not one I had used. It seems they also let developers open projects where the LightswitchVersion XML element is 4.5.
I hope this post saves someone else a little time. If you can shed any light on why installing the office developer tools upgrades a Lightswitch project to version 4.5, please leave a comment.