Developing an Outlook Addin 2010 with Visual Studio 2012, having Office 2013 Installed

Question

Ok, this is tricky.

I have been for months maintaining an Outlook 2010/2013 add-in using Visual Studio 2012 in my dev machine. In my dev machine I had installed just Office 2010. In order to test it in 2013, I used to move my code to another machine with Office 2013 installed, than if something changed, merge back the changes in my code. This worked for months. I was even able to build both solutions, targeting 2010 and 2013 in my computer and create setup files.

Last week I installed Office 2013 in my computer. I made changes to the Outlook 2013 addin, and was getting ready to build the solutions. To my surprise when I try to open the same old project Outlook 2010 Addin in Visual Studio 2012, I receive a message about upgrade my solution, like if it was a solution created in a previous VS version, which is not, I haven't touched my VS installation for the whole past year.

If I proceed to the upgrade, and I review the new project/solution I notice it was upgraded to target Outlook 2013, which I don't want, since I already have another project for that.

Why is this happening? Why all of the sudden an static .sln/.csproj file is not not recognizable for VS 2012 as they we working before I installed Office 2013?

Answer 1

If you open the solution on a PC with a different version of Office installed, it will fail to bind to the references for that specific version of Office and you'll have to change the references manually. However, if you embed the assemblies you can still deploy it for other versions of Outlook (provided that you aren't using elements of the Object Model that isn't available for that version).