AddIn Error: Unable to cast COM object of type 'System. ComObject' RRS feed

  • Question

  • I have an addin that I've been working on for several years. I recently switched to a new development machine. After working for a while I realized I installed Project 2016 and I need the addin to work on 2013.  So I uninstalled 2016 and installed 2013.  Nowwhen I the Addin I get this error:

    Unable to cast COM object of type 'System. ComObject' to interface type 'Microsoft.Office.lnterop.MSProject.Project'. This operation failed because the Querylnterface call on the COM component for the interface with IID '{00020800 0000 COCO-COCO 000000000046)' failed due to the following error: No such interface supported (Exception from HRESULT: Ox80004002 

    I tried googling and I think somehow I have a bad registry version for the InterOp DLL but I can't figure out a solution. I triedreinstalling VSTO too.


    Sunday, February 25, 2018 7:54 PM