You may get this sort of error if you change compiler. What you should do is remove the reference from the project:
Then add a reference, browsing to the file Autodesk.Inventor.Interop.dll .
The whole horrible message is this:
warning MSB3277: Found conflicts between different versions of "Autodesk.Inventor.Interop" that could not be resolved.
warning MSB3277: There was a conflict between "Autodesk.Inventor.Interop, Version=23.0.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564" and "Autodesk.Inventor.Interop, Version=23.2.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564".
warning MSB3277: "Autodesk.Inventor.Interop, Version=23.0.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564" was chosen because it was primary and "Autodesk.Inventor.Interop, Version=23.2.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564" was not.
warning MSB3277: References which depend on "Autodesk.Inventor.Interop, Version=23.0.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564" [C:\Program Files\Autodesk\Inventor 2019\Bin\Public Assemblies\Autodesk.Inventor.Interop.dll].
warning MSB3277: C:\Program Files\Autodesk\Inventor 2019\Bin\Public Assemblies\Autodesk.Inventor.Interop.dll
warning MSB3277: Project file item includes which caused reference "C:\Program Files\Autodesk\Inventor 2019\Bin\Public Assemblies\Autodesk.Inventor.Interop.dll".
warning MSB3277: Autodesk.Inventor.Interop, Version=23.0.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564, processorArchitecture=MSIL
warning MSB3277: References which depend on "Autodesk.Inventor.Interop, Version=23.2.0.0, Culture=neutral, PublicKeyToken=d84147f8b4276564" [C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\Autodesk.Inventor.Interop\v4.0_23.2.0.0__d84147f8b4276564\Autodesk.Inventor.Interop.dll].
warning MSB3277: C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Automation.dll
warning MSB3277: Project file item includes which caused reference "C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Automation.dll".
warning MSB3277: Autodesk.iLogic.Automation
warning MSB3277: C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Interfaces.dll
warning MSB3277: Project file item includes which caused reference "C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Interfaces.dll".
warning MSB3277: Autodesk.iLogic.Automation
warning MSB3277: C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Types.dll
warning MSB3277: Project file item includes which caused reference "C:\Program Files\Autodesk\Inventor 2019\Bin\Autodesk.iLogic.Types.dll".
warning MSB3277: Autodesk.iLogic.Automation