Our development team (and build servers) successfully use a mixture of Visual Studio 2010 and Visual Studio 2012 for our application.
However, since upgrading from EF5 to EF6, we no longer seem to be able to build with VS2010. Specifically, the build machines won't build at all. VS2010 on my desktop does seem to build, but I get the following errors:
Error 4 Error 10023: Could not find the conceptual model to validate. Error 5 Error 10024: Could not find the storage model to validate. Error 6 Error 10025: Could not find the mapping model to validate.
Our build machines do not have .Net 4.5, our Desktop machines (due to IT policy) do have .Net 4.5. On the machines without 4.5, we also get the following, which prevent assembly generation.
Could not find the Conceptual Schema node to embed as a resource for input file
You can use EF6 runtime with .NET Framework 4/Visual Studio 2010 however EF6 tooling does not support VS2010. EF tooling was updated to work with EF6 for VS2012 and VS2013. In other words on VS2010 and EF6 you can do CodeFirst but not ModelFirst/DatabaseFirst.