VSTO & .NET & Excel

April 8, 2007

Requirements VSTO solutions

Filed under: VSTO & Excel — Dennis M Wallentin @ 1:49 am

It seems that it’s still existing some confusion regarding what it actually requires to develop and use VSTO solutions and also which versions of Office are supported. This blogpost will try to give a better overview of VSTO.

At present there exist two versions of VSTO, 2005 and 2005 Second Edition (VSTO 2005 SE).

VSTO 2005 can either be used standalone or ‘on top’ of Visual Studio 2005 Professional and higher. It requires that we buy a license of it in order to use it.

With VSTO 2005 we can:

  • Create workbook’s level solutions, i e standalone workbooks and templates with managed code (VB.NET / C#) behind for Excel 2003 (and Excel 2007).

VSTO 2005 SE is available free for download. In order to use it we either need VSTO 2005 or Visual Studio 2005 Professional and higher. 

What we can do with VSTO 2005 SE:

  • Create managed COM Add-ins (VB.NET/ C#) for Excel 2003 and Excel 2007

The following list shows the requirements on the development computer:


The following list shows the required Office version for each version of VSTO (and on the development computer):


Note 3 above is important as we cannot explicit use VSTO 2005 with Excel 2007 to develop workbook’s level solutions. The workaround is to use Excel 2003 and then test the solutions with Excel 2007.

Note 4 above, I did test to have Office 2003 and Office 2007 installed side by side together with VSTO 2005 SE but it only ended up in a critical error message.

The following list shows the requirements on the targeting computers:


Finally, I have an article, that is regular updated, about online resources for VSTO here which includes all the relevant links for the above. 

Kind regards,



  1. I’m trying to deploy an Excel 2003 Add-In to a non-development pc, ending up with Excel not loading the Add-in. I think I got the registry settings correct, but when Excel starts to load the actual DLL it just stops doing that at some point, and sets the LoadBehavior registry key to 2.

    With a File monitor, I can see Excel copying the .dll, .pdb and the manifest files to a temp dir in Local Settings, and then just dies.

    Has anyone ever encountered this problem before ?

    Comment by Jejo — May 9, 2007 @ 7:09 pm

  2. In my experience it’s probably related to the CAS settings for the project.

    Kind regards,

    Comment by Dennis Wallentin — May 9, 2007 @ 7:32 pm

  3. Hi,
    I have an excel 2003 VSTO project .
    When I try open the spreadsheet with office 2007 i am getting the error: “Method not found: Microsoft.Office.Interop.Excel.FormatCondition” Any suggestions please?

    Comment by Jonathan — July 6, 2007 @ 12:15 pm

  4. Jonathan,

    What You can test is to check the code in VBA in Excel 2007 to see if it work or not. If working then You need to make sure You apply the format conditions correctly in VSTO.

    Kind regards,

    Comment by Dennis Wallentin — July 8, 2007 @ 6:26 pm

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