What happened to CharacterMotor in 3.4?

This error indicates the script CharacterMotor.js was not found, or has not been compiled yet. When a script is compiled, Unity creates a new type with the same script name (but without quotes or extension), which is not being found at this compilation stage. Could it be caused by compilation order? (take a look here)

EDITED: To be more specific: CharacterMotor.js doesn't exist in your project, but the script Khelna_FPSController.js declares the variable motor with this type. (CharacterMotor.js is a script used in the Assets/Standard Assets/Character Controllers/First Person Controller).
At the end of 3.4 What's New, they mention that improved type checking could cause some scripts ok in 3.3 to produce errors in 3.4.
You have two alternatives: import the package Character Controller to your project (menu Assets/Import Package...) or remove the script Khelna_FPSController.js from the Assets folder, if you're not using it at all (every script in Assets or its subfolders is compiled and must be free of errors, even if you don't ever use it).