What causes "Scene path cannot be null or empty." in Unity-Technologies/UnityCsReference?

Validate the scene path is non-empty before calling, and skip or report the offending entry.

Unity-Technologies/UnityCsReference · error · ArgumentNullException

Scene path cannot be null or empty.

Error message

Scene path cannot be null or empty.

What it means

Thrown by LoadableSceneIdEditorUtility.CreateLoadableSceneId(string) when scenePath is null or empty. It is a defensive guard at the top of the factory that builds a LoadableSceneId handle from a scene asset path.

Source

Thrown at Editor/Mono/Loadable/LoadableSceneIdEditorUtility.cs:68

                return null;
            return AssetDatabase.LoadMainAssetAtGUID(guid) as SceneAsset;
        }

        /// <summary>
        /// Create a LoadableSceneId object based on a scene's path.
        /// </summary>
        /// <param name="scenePath">The scene's path within the project. Must end with .unity extension.</param>
        /// <returns>A LoadableSceneId handle populated to reference the provided scene.</returns>
        /// <exception cref="System.ArgumentNullException">
        /// Thrown if scenePath is null or empty.
        /// </exception>
        /// <exception cref="System.ArgumentException">
        /// Thrown if the path doesn't end with .unity extension or if the scene asset cannot be found at the specified path.
        /// </exception>
        public static LoadableSceneId CreateLoadableSceneId(string scenePath)
        {
            if (string.IsNullOrEmpty(scenePath))
                throw new ArgumentNullException(nameof(scenePath), "Scene path cannot be null or empty.");
            if (!scenePath.EndsWith(".unity", StringComparison.CurrentCultureIgnoreCase))
                throw new ArgumentException($"Path {scenePath} is not a scene path. Must end with .unity extension.");
            var guid = new GUID(AssetDatabase.AssetPathToGUID(scenePath));
            if (guid.Empty())
                throw new ArgumentException($"Couldn't locate scene asset at path {scenePath}");
            return CreateLoadableSceneId(guid);
        }
    }
}

View on GitHub (pinned to 225b0fbdb5)

Solutions

Validate the scene path is non-empty before calling, and skip or report the offending entry.
Fix the source of the path (serialized reference, config, inspector field) so it is populated.
Provide a clear error to the user identifying which scene entry is missing its path.

Example fix

// before
var id = LoadableSceneIdEditorUtility.CreateLoadableSceneId(scenePath);

// after
if (string.IsNullOrEmpty(scenePath))
    throw new InvalidOperationException("Scene reference is unassigned in build list.");
var id = LoadableSceneIdEditorUtility.CreateLoadableSceneId(scenePath);

Defensive patterns

Strategy: validation

Validate before calling

if (string.IsNullOrEmpty(scenePath)) throw new InvalidOperationException("Scene path is unassigned.");

Type guard

static bool IsValidScenePath(string p) => !string.IsNullOrEmpty(p);

Try / catch

try { CreateLoadableSceneId(scenePath); }
catch (ArgumentNullException) { Debug.LogError("Scene path missing; check the source reference."); }

Prevention

Validate scene paths from config before use
Use SceneAsset references over stored strings
Report which entry is missing

When it happens

Trigger: Calling CreateLoadableSceneId with a null or empty string — e.g. a serialized field that was never assigned, a path read from a broken reference, or a config value left blank.

Common situations: Editor tooling or build scripts that consume a scene list from a configuration object where an entry is unset. A SceneAsset reference that resolved to a null path after the asset was moved or deleted.

Related errors

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/e174875d0b126dd0. Report an issue: GitHub.