Microsoft Interop Assembly for Excel Fails

a b 1 Reputation point
2020-09-25T20:22:31.843+00:00

Does Microsoft.Office.Interop.Excel work in x64 and Any CPU modes after updating MS Office 2019? My application fails when attempting to add a workbook with:

Unable to cast COM object of type 'Microsoft.Office.Interop.Excel.ApplicationClass' to interface type 'Microsoft.Office.Interop.Excel._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}' failed due to the following error: Element not found. (Exception from HRESULT: 0x8002802B (TYPE_E_ELEMENTNOTFOUND)).

I've included the assembly via a reference to 'Microsoft Excel 16.0 Object Library' in the Com reference area. When I query the Excel application object, I see the following (only a partial list):

?cfExcel
{Microsoft.Office.Interop.Excel.ApplicationClass}
ActiveCell: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveCell' threw an exception of type 'System.InvalidCastException'
ActiveChart: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveChart' threw an exception of type 'System.InvalidCastException'
ActiveDialog: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveDialog' threw an exception of type 'System.InvalidCastException'
ActiveEncryptionSession: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveEncryptionSession' threw an exception of type 'System.InvalidCastException'
ActiveMenuBar: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveMenuBar' threw an exception of type 'System.InvalidCastException'
ActivePrinter: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActivePrinter' threw an exception of type 'System.InvalidCastException'
ActiveProtectedViewWindow: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveProtectedViewWindow' threw an exception of type 'System.InvalidCastException'
ActiveSheet: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveSheet' threw an exception of type 'System.InvalidCastException'
ActiveWindow: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveWindow' threw an exception of type 'System.InvalidCastException'
ActiveWorkbook: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).ActiveWorkbook' threw an exception of type 'System.InvalidCastException'
AddIns: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).AddIns' threw an exception of type 'System.InvalidCastException'
AddIns2: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).AddIns2' threw an exception of type 'System.InvalidCastException'
AlertBeforeOverwriting: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).AlertBeforeOverwriting' threw an exception of type 'System.InvalidCastException'
AltStartupPath: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).AltStartupPath' threw an exception of type 'System.InvalidCastException'
AlwaysUseClearType: 'DirectCast(cfExcel, Microsoft.Office.Interop.Excel.ApplicationClass).AlwaysUseClearType' threw an exception of type 'System.InvalidCastException'

My application is compiled for 'Any CPU' and each project does not have the 'Prefer 32 bit' property set.

Any suggestions?

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  1. Dave Patrick 426.1K Reputation points MVP
    2020-09-25T20:27:11.147+00:00

    Excel development is not currently supported here on QnA. They're actively answering questions in dedicated forums here.
    https://answers.microsoft.com/en-us/msoffice/forum/msoffice_excel-msoffice_custom
    https://social.msdn.microsoft.com/Forums/Lync/en-US/home?forum=exceldev
    https://social.msdn.microsoft.com/Forums/vstudio/en-US/home?forum=vsto

    --please don't forget to Accept as answer if the reply is helpful--

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