The root cause of File not in sync errors is usually ‘dirty’ serialization caused by runtime scripts modifying a Prefab asset. When frameworks dynamically add components or change values on a Prefab instance and mark the asset as dirty, the version control metadata becomes inconsistent.

To resolve these synchronization errors, follow these steps:

1. Identify the dynamic component causing the mismatch. This is often a NavMeshAgent or NetworkObject created via code.
2. Open your Prefab in Isolation Mode (Prefab Stage) and ensure no temporary components are listed in the Inspector.
3. Review your script and ensure any AddComponent calls or property modifications on persistent assets are either wrapped in #if UNITY_EDITOR checks or utilize HideAndDontSave flags to prevent serialization.
4. If your File not in sync error persists, right-click the Prefab in the Project Window and select Version Control > Revert to clear the local metadata mismatch.
5. In the Project Settings, verify that Version Control is set to use Visible Meta Files to allow your version control system to track serialization changes accurately.

Additional Tips

• Use EditorUtility.SetDirty sparingly and only when actual persistent data changes are required.
• Consider using Prefab variants for runtime configurations instead of modifying base assets dynamically.
• Ensure your .gitignore or .plasticignore is not accidentally excluding .meta files associated with your Prefab assets.