If you are working with our code from the source code repository and you get the latest changes it may break your custom solutions from building, but the problem can be easily corrected.
We made changes to make it possible to use .NET 4.5 going forward while still being able to build for .NET 4 (and 3.5).
There is a new .sln file mojoPortal.Web.net40.sln
and there are new .csproj files for mojoPortal.Web.net40.csproj, WebStore.UI.net40.csproj, and mojoPortal.Features.UI.net40.csproj
the main versions of those .csproj files (mojoPortal.Web.csproj, mojoPortal.Features.UI.csproj, and WebStore.UI.csproj) have all had their target framework changed to .NET 4.5.
So you have a choice with your own projects that may reference these projects. Either change your target as needed to .NET 4.5 to keep using the main project references, or remove the project from your solution and and the .NET 4 version of the csproj files instead to keep working with your own project targeting .NET 4.0.
I realize this may be a little inconvenient but I think we need to be able to move forward with some of the things only possible using the latest .NET, including things like Web API (which I am digging into now to see what we can do to make it easy for you to add your own routes and develop your own apis that can plugin). If you run into any problems fixing your own projects so they build again we'll try to help.
I think we will stop shipping packages for .NET 3.5 but it will still be possible to build a package from source code for a while if someone really needs one.
I'm still a little unclear about the hosting situation with .NET 4 vs 4.5 or how to be sure which one is running. For now my plan is to ship 2 packages or at least a separate set of .NET 4 compatible dlls for anyone who may get an error with our main 4.5 package that will ship at the next release. I'm hoping most .NET 4 hosting has updated to 4.5 as they should.
Beyond that I'm pretty excited about .NET vnext which will come later (currently it is alpha release). After .NET vnext ships we should be able to support Linux/Mono again since the whole .NET framework is going to be open source and intended to just work on Mono. And the new options to pre-compile everything to native code is going to make things dramatically faster for start up time of web apps.