InfoPath Dev

I get this error when trying to save a form created in 2013 to 2010. There is some C# code. The error message says to remove it...  Is there some secret way to convince Infopath that the language is supported?

 Or maybe I can just edit the xsf to allow it to open in FormFiller 2010 somehow?

 I wonder if it is because the code project is targeting .NET 4.0? That is (I think) the default when the code is created from IP 2013. Can you try changing that to .NET 2.0? Right click the project in Solution Explorer in Visual Studio 2012 and select properties and try changing the Target framework in the Application category.

I tried that then my project wouldn't build because it references Microsoft.Office.InfoPath from Office 15

and I get the compiler error saying "The type or namespace name 'Office' does not exist in the namespace 'Microsoft' (are you missing an assembly reference?)"

Same for LoadingEventArgs and XmlEventArgs, so I guess the Infopath DLL was different in 2010. 

I am currently re-installing IP & VSTA 2010. 

Oh, the joys of trying to use the latest technology in a big beaurocratic organisation :-(

I guess I'd copy the code from the code file, use remove code on the form, change the form compatibility, then re-add my code - I'm currently using VS 2012 and IP 2013 on an IP 2003 compatible form, so I am having success using the latest dev enviro for earlier versions.