Clean and rebuild the solution. Remove and re-add the reference to autodesk.inventor.interop.dll . Ensure you are not mixing interop DLLs from different Inventor versions. Error 4: Mixed Mode Assembly Is Built Against Version 'v2.0.50727' Causes: This legacy error appears when you reference an older interop DLL built against .NET 2.0 while your project targets .NET 4.x or newer.
Add the following to your app.config file: autodesk.inventor.interop.dll
Introduction In the world of Computer-Aided Design (CAD) automation, few file names evoke as much technical curiosity—and occasional frustration—as autodesk.inventor.interop.dll . If you are a software developer, a systems integrator, or a power user who works with Autodesk Inventor, you have likely encountered this dynamic link library (DLL). Whether it appears as a reference in your .NET project, as a missing file error on your workstation, or as part of a complex add-in, understanding this DLL is critical for successful CAD automation. Clean and rebuild the solution
When respected and used correctly, this humble interop assembly unlocks the full potential of Inventor customization, from simple parametric updates to complex generative design workflows. Treat it as a bridge, not a permanent fixture in your output folder, and you will avoid the most common mistakes that plague CAD automation developers. Error 4: Mixed Mode Assembly Is Built Against Version 'v2