Microsoft.Office.Interop.Excel._Application

What does this mean:

Bonus Tools error occurred here: Helper: getExel. Error: System.InvalidCastException: 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)).   at System.StubHelpers.StubHelpers.GetCOMIPFromRCW(Object objSrc, IntPtr pCPCMD, IntPtr& ppTarget, Boolean& pfNeedsRelease)   at Microsoft.Office.Interop.Excel.ApplicationClass.get_Version()   at Helper.getExel().

In short this is a Microsoft issue, and has been since I started Bonus Tools back in 2010, and will effect other Revit addins like Dynamo. 

This problem appears after uninstall a MSOffice version, a restart is NOT made immediately and automatically a new install of a new version of MSOffice is done. The Windows registry is not cleaned up. Happily, after a restart is made, the Modify/Repair of MSOffice in Control panel/Programs and features solves this problem. I too get this issue.

Performing a Office repair resolves the issue on my PC every time it happens. Please follow these steps:

1. Close ALL applications
2. Go to Add or Remove Programs
3. Type 365 to search for Microsoft 365 (Office).
4. Click on the ellipses and Modify. Ensure you select the correct one from the list.
5. Select Quick Repair
6. 
7. Follow the steps
8. Restart your PC once complete.