More information about features that have changed and may affect your project when upgrading from Unity 4 to Unity 5
Cursor lock and cursor visibility are now independent of each other.
// Unity 4.x
Screen.lockCursor = true;
// Becomes this in Unity 5.0
Cursor.visible = false;
Cursor.lockState = CursorLockMode.Locked;
Gamepad handling has been reworked for Unity 5.
Unity is now capable of “configuring” gamepads - either via a database of known models, or using the SDL_GAMECONTROLLERCONFIG environment variable, which is set by Steam Big Picture / SteamOS for gamepads detected or configured with its interface.
Configured gamepads present a consistent layout: left stick uses axes 0/1, right stick uses axes 3/4, buttons on the face of the gamepad are 0–3, etc. To determine whether a gamepad has been configured, call Input.IsJoystickPreconfigured().
‘Metro’ keyword was replaced to ‘WSA’ in most APIs, for example: BuildTarget.MetroPlayer became BuildTarget.WSAPlayer, PlayerSettings.Metro became PlayerSettings.WSA.
Defines in scripts like UNITY_METRO, UNITY_METRO_8_0, UNITY_METRO_8_1 are still there, but along with them there will be newer defines UNITY_WSA, UNITY_WSA_8_0, UNITY_WSA_8_1.
UnityEngine.AnimationEvent is now a struct. Comparisons to ‘null’ will result in compile errors.
AddComponent(string), when called with a variable cannot be automatically updated to the generic version AddComponent<T>(). In such cases the API Updater will replace the call with a call to APIUpdaterRuntimeServices.AddComponent(). This method is meant to allow you to test your game in editor mode (they do a best effort to try to resolve the type at runtime) but it is not meant to be used in production, so it is an error to build a game with calls to such method). On platforms that support Type.GetType(string) you can try to use GetComponent(Type.GetType(typeName)) as a workaround.
AssetBundle.Load, AssetBundle.LoadAsync and AssetBundle.LoadAll have been deprecated. Use AssetBundle.LoadAsset, AssetBundle.LoadAssetAsync and AssetBundle.LoadAllAssets instead. Script updater cannot update them as the loading behaviors have changed a little. In 5.0 all the loading APIs will not load components any more, please use the new loading APIs to load the game object first, then look up the component on the object.
The internal package format of .unityPackages has changed, along with some behaviour of how packages are imported into unity and how conflicts are resolved.
Packages are now only constructed with the source asset and the .meta text file that contains all the importer settings for the asset.
Packages will always require asset importing now.
Packages will be reduced in size significantly, because the imported data (for example texture and audio data) will not be doubled up.
Packages with file names that already exist in the project, but with different GUIDs will have these files imported with a unique file name. This is done to prevent overriding files in the project that actually came from different packages or were created by the user.