Some assemblies might be relying on a specific higher version of Autodesk.Inventor.Interop.dll than the one your project is referencing. That's the problem I ran into with Autodesk.iLogic.Core.dll in case of the project talked about here: Get iLogic Form information from Inventor documents
My project was working fine, but when I installed the latest Inventor 2020 update and tried to compile my project, I got this error:
Assembly 'Autodesk.iLogic.Core' with identity 'Autodesk.iLogic.Core, Version=24.30.37300.0, Culture=neutral, PublicKeyToken=null' uses 'Autodesk.Inventor.Interop, Version=220.127.116.11, Culture=neutral, PublicKeyToken=d84147f8b4276564' which has a higher version than referenced assembly 'Autodesk.Inventor.Interop' with identity 'Autodesk.Inventor.Interop, Version=18.104.22.168, Culture=neutral, PublicKeyToken=d84147f8b4276564'
You can find the various versions of Autodesk.Inventor.Interop.dll in the "C:\Windows\Microsoft.NET\assembly\GAC_MSIL\Autodesk.Inventor.Interop" folder including version 24.2 (after installing the relevant Inventor update):
Once I added that reference, the project compiled fine. 😀