I have installed Visual Studio 2010 and Office 2007. When I go to “Add Reference” and search for “Office Interop” I can see that each of the references appear twice with versions 12 and 14.
I initially tried version 14 of Microsoft.Office.Interop.Word and did a quick test. Initialise the Application, open a Document, close the Document, quit the Application, and release the COM object. My test was a simple WinForms program in C# 4.0.
WINWORD.EXE crashed while closing the document.
I switched the reference to version 12, and left my code exactly as it was and tried it again. Everything worked fine.
I have since written the rest of my code using version 12 and haven’t had any problems.
So now I’m curious: There are some small differences between the publicly exposed members in Microsoft.Office.Interop.* in versions 12 and 14, but largely there is a lot of overlap.
What is the actual difference? Why did my simple test fail even though I have a relatively new version of Office? and is there a rule-of-thumb as to which version should the developer choose when starting an interop project?
Version 12 is interop for Office 2007, while 14 is for Office 2010. AFAIK, unless you really need some new features of 14th version, you can use a lower version of interop library and it will work fine for all newer versions of Office.