This is a distressingly common error for owners of legitimate copies.
Navigate to: HKEY_CURRENT_USER\Software\KnifeEdge\RealFlight\6.5 real flight 65 serial number updated
Running into an error code is a common hurdle when reinstalling legacy software like RealFlight 6.5. Here is how to resolve the most common snags: 1. "Invalid Serial Number" This is a distressingly common error for owners