I developed an Excel VSTO add-in in Visual Studio 2010. It works fine on different combinations of Windows 7+ and Excel 2007+, but fails to load on Windows XP and Excel 2007 with a non-informative "A runtime error occurred during the loading of the COM Add-In" message. VSTO_SUPPRESSDISPLAYALERTS=0 and VSTO_LOGALERTS=1 produce no data.
After debugging with API Monitor and Dependency Walker, I found the following. In order to load the add-in, Excel loads C:\Program Files\Common Files\Microsoft Shared\VSTO\10.0\VSTOLoader.dll. This library imports GetFileVersionInfoEx function from C:\Windows\System32\Version.dll, which is available only starting with Vista. So loading of my add-in DLL is not even attempted, since the process fails very early during loading of VSTO Runtime.
Any ideas on how to fix this? Am I missing some dependency? Here is what I have installed so far:
I too ran into this bothersome issue.
For those of us still supporting clients on XP, you can still use the previous release VSTO 10.0.50903 without this issue.
While Microsoft has hid the old download detail pages, you can still find the prior release at this very deep link:
http://download.microsoft.com/download/C/0/0/C001737F-822B-48C2-8F6A-CDE13B4B9E9C/vstor_redist.exe
Funny note, System requirements for the new VSTO 10.0.60724 version still note "Windows XP (x86) with Service Pack 3 - all editions except Starter Edition" is still a Supported Operating System. As you point out, this is sadly incorrect.