The DLL is installed automatically with Autodesk Inventor. You can find it at the following default paths: Primary Location:
If your add-in must support Inventor 2022, 2023, and 2024, do reference a single autodesk.inventor.interop.dll . Instead: autodesk.inventor.interop.dll
Unlike late-binding approaches ( dynamic in C# or CreateObject in VB6), this interop gives you IntelliSense, compile-time checking, and explicit interfaces. When you type _Document , you immediately see SaveAs , Close , ModelReference , etc. This drastically reduces runtime errors. The DLL is installed automatically with Autodesk Inventor
Missing or incorrect reference to the interop assembly. The .NET runtime cannot map the native COM interface to a managed type. this interop gives you IntelliSense
Always set Copy Local = False for autodesk.inventor.interop.dll .
The DLL is typically installed alongside Inventor in the following directory: