Unlike major content drops like version 13.0.0 (which introduced Sora), version 13.0.3 is a technical maintenance patch.

: Replays from versions 9.0.0 through 13.0.2 may have compatibility issues with this new version. It is highly recommended to convert your critical replays to video via Vault → Replays → Replay Data → Convert to Video before applying the update. Portable and NSP Considerations

For players using the NSP format to manage their game data on "portable" setups or emulators, specific steps are required to maintain a functional game environment.

Super Smash Bros. Ultimate Update 13.0.3: Key Fixes and Performance Guide