Class not registered error when creating Excel workbook in C#

Question

When I try to access an Excel spreadsheet using the following code I get a \"Library not registered\' error when defining the workbook object wrkbuk using C# from Visual Studio

Answer 1

Something which hasn't been mentioned here but which may be useful is that subkeys of 1.XX can cause issues as well. For example: Under Computer\HKEY_CLASSES_ROOT\TypeLib{00020813-0000-0000-C000-000000000046} I had the subkey 1.9. This in turn has the subkey 0(or should). Now under this, there were two subkeys - Win32 and Win64. As a result, Visual Studio was unable to resolve the location of Microsoft.Office.Interop.Excel.dll - it was reading two subkeys where it could only read one. Deleting the Win32 subkey fixed my issue completely. Please note that this was done after a complete reinstall of VS 2017 & Office 365 Pro Plus. Hope this helps someone.