The Code Conversion Utility may have broken a wire path contained within a string wired to a node on the diagram.
The Code Conversion Utility generates new files in the output directory, which may cause relative and absolute paths to be incorrect.
If the previous suggestions don't restore the functionality of the affected code and the code isn't essential to the core functionality of your application, you can remove the portion of code. If the code is part of the core functionality of the application, you can use the VI Interop node to call your existing code, provided that the new code organization meets the architectural goals of your application. If neither solution meets the requirements of your application, do not migrate to LabVIEW NXG at this time.