Unity-Technologies/UnityCsReference · error · ArgumentNullException

materialFolderPath

Error message

materialFolderPath

What it means

SpeedTreeImporter.SearchAndRemapMaterials(string materialFolderPath) walks a folder for Material assets and remaps them onto the importer's source materials. A null path is rejected up front with ArgumentNullException because AssetDatabase.FindAssets would otherwise throw a less specific NullReferenceException internally. The path is the search root, so null is always a programmer error, never a valid 'search everywhere' sentinel.

Source

Thrown at Editor/Mono/AssetPipeline/SpeedTreeImporter.bindings.cs:219

        {
            [NativeName("MaterialsShouldBeRegenerated")]
            get;
        }

        internal extern void SetMaterialVersionToCurrent();

        internal extern SourceAssetIdentifier[] sourceMaterials
        {
            [FreeFunction(Name = "SpeedTreeImporterBindings::GetSourceMaterials", HasExplicitThis = true)]
            get;
        }

        public bool SearchAndRemapMaterials(string materialFolderPath)
        {
            bool changedMappings = false;

            if (materialFolderPath == null)
                throw new ArgumentNullException("materialFolderPath");

            if (string.IsNullOrEmpty(materialFolderPath))
                throw new ArgumentException(string.Format("Invalid material folder path: {0}.", materialFolderPath), "materialFolderPath");

            var guids = AssetDatabase.FindAssets("t:Material", new string[] { materialFolderPath });
            List<Tuple<string, Material>> materials = new List<Tuple<string, Material>>();
            foreach (var guid in guids)
            {
                var path = AssetDatabase.GUIDToAssetPath(guid);
                // ensure that we only load material assets, not embedded materials
                var material = AssetDatabase.LoadMainAssetAtPath(path) as Material;
                if (material)
                    materials.Add(new Tuple<string, Material>(path, material));
            }

            var importedMaterials = sourceMaterials;
            foreach (var material in materials)
            {

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Pass an explicit material folder path string such as "Assets/MyProject/Materials".
2. If the folder is optional, branch on null before calling and skip/search a default location instead.
3. Validate the path at the UI/setting layer so a null never reaches the API.

Example fix

// before
importer.SearchAndRemapMaterials(materialFolder); // materialFolder may be null

// after
if (string.IsNullOrEmpty(materialFolder))
    throw new InvalidOperationException("Material folder not configured.");
importer.SearchAndRemapMaterials(materialFolder);

if (materialFolderPath == null)
    throw new InvalidOperationException("materialFolderPath not set");
importer.SearchAndRemapMaterials(materialFolderPath);

static bool IsUsableFolderPath(string p) => p != null;

When it happens

Trigger: Calling SearchAndRemapMaterials(null); passing a path variable that was never initialized or came from a null config field; a UI text field bound to the argument with no value entered.

Common situations: Editor tooling that drives remapping from a project setting that is unset; scripts that derive the folder from selection when nothing is selected; migration where the expected folder constant was removed.

Related errors

• path
• paths
• type
• name
• Invalid material folder path: {0}.

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/cbcb90a6f9071e02. Report an issue: GitHub.