Why do Office updates break the Excel interop?

Question

I'm writing Selenium automation in C# in Visual Studio 2019, and have a Microsoft Office 16.0 Object Library COM reference so that I can open Excel sheets and read in data. The version of Excel I'm using is "Microsoft Excel for Microsoft 365 MSO (16.0.13801.21198) 32-bit".

The Excel code works fine until certain Office updates are rolled out to my machine, at which point I start getting this error when trying to open a worksheet:

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.

I've seen various recommendations to try deleting a registry entry in order to fix this, which have not worked. The only way I can get it working again is to run a Quick Repair on Office 365.

This is happening every week or two, and I have a number of automation developers on my team who have the same issue and need to run a Quick Repair in order to fix it.

Does anyone know exactly what causes this problem? I'd really prefer to develop a solution or workaround for it that doesn't require manually firing off a repair to Office all the time.

Note: I have tried switching to the Excel.Interop nuget package and using that dll instead but I still have the same issue after an Office update.

Answer 1

I think that switching to a package that doesn't use a COM object might work. When I ran into a problem sort of like this I switch to using EPPLus it is licened but you can use it without if it is not comercial.