| Catalog missing, empty or stale |
Definitions/IDs/prefabs are missing, duplicated or changed |
Generate or assign definitions; select the catalog and use Run Catalog Validation. Keep Character IDs stable. The built-in lobby selection requires a valid catalog with Gameplay Prefabs, even if your gameplay uses existing/custom objects. |
| Too few player panels |
Supplied visuals have four slots, or authored roots are missing |
Use Existing Canvas with one complete root per configured player, or reduce the supplied-lobby capacity. |
| Controller does not join |
Capacity is full/reserved, device is unavailable, or its layout/profile does not match |
Check Unity Input Debugger, the assigned profile and its Join binding. A profile-matched HID must expose the required controls. Identical display names are not device identity. See device recovery. |
| Start Game unavailable |
A joined player is not Ready, input is unavailable, or no player is joined |
Confirm each player; reconnect reserved input or intentionally Leave that session. Check the target scene is enabled in the scene list used by the active Build Profile. |
| Existing Canvas cannot apply |
Required assignments, hierarchy boundaries or saved scene are missing |
Use each Player panel entry; assign fields marked * and resolve listed errors. Optional labels/graphics can stay empty. |
| Gameplay has no player objects/input |
API-only mode is selected, representation references are missing, or no input mode is configured |
Configure Gameplay Player Setup and Gameplay Player Binding, or consume GameplayPlayers through your own integration. Follow the isolated runtime diagnostic. |
| Split Screen has no views/follow |
Representations or a camera source/follow script are missing |
Resolve gameplay objects, assign the camera prefab/representation/provider, and supply follow behavior. See Chapter 10 — Shared and Split Screen Cameras. |
| Smart UI compatibility warning |
Older, missing, mixed or unvalidated shared module |
Back up local edits; restore a complete compatible revision. Use Tools > LevelArgento > Couch Co-op Builder > Validate Smart UI Compatibility. No automatic repair occurs. |