Unity-Technologies/UnityCsReference · error · Exception

Required property 'name' not set

Error message

Required property 'name' not set

What it means

Thrown by CustomScriptAssembly.ValidateFields: an assembly definition (.asmdef) is valid only if its 'name' field is a non-empty string. A missing or blank name is rejected before the assembly is registered.

Source

Thrown at Editor/Mono/Scripting/ScriptCompilation/CustomScriptAssembly.cs:124

        public static CustomScriptAssemblyData FromJsonNoFieldValidation(string json)
        {
            var assemblyData = new CustomScriptAssemblyWithLegacyData();
            assemblyData.autoReferenced = true;
            UnityEngine.JsonUtility.FromJsonOverwrite(json, assemblyData);

            UpdateRenamedReferences(assemblyData);
            assemblyData.UpdateLegacyData();

            if (assemblyData == null)
                throw new System.Exception("Json file does not contain an assembly definition");

            return assemblyData;
        }

        public void ValidateFields()
        {
            if (string.IsNullOrEmpty(name))
                throw new System.Exception("Required property 'name' not set");

            if ((excludePlatforms != null && excludePlatforms.Length > 0) &&
                (includePlatforms != null && includePlatforms.Length > 0))
                throw new System.Exception("Both 'excludePlatforms' and 'includePlatforms' are set.");

            if (autoReferenced && UnityCodeGenHelpers.IsCodeGen(name))
            {
                throw new Exception($"Assembly '{name}' is a CodeGen assembly and cannot be Auto Referenced");
            }
        }

        public static string ToJson(CustomScriptAssemblyData data)
        {
            return UnityEngine.JsonUtility.ToJson(data, true);
        }

        static void UpdateRenamedReferences(CustomScriptAssemblyData data)
        {

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Open the .asmdef referenced in the error and add a non-empty "name" field.
2. Validate .asmdef JSON before import (the editor will surface the file path).

Example fix

// before
{ "references": [] }
// after
{ "name": "MyCompany.MyFeature", "references": [] }

if (string.IsNullOrEmpty(data.name))
    throw new FormatException("Assembly definition is missing the required 'name' field.");

static bool HasName(CustomScriptAssemblyData d) =>
    !string.IsNullOrEmpty(d?.name);

try { asm.ValidateFields(); }
catch (Exception ex) when (ex.Message.Contains("'name'"))
{ /* open the .asmdef and add a non-empty name */ }

When it happens

Trigger: Loading a .asmdef whose 'name' field is null or empty, then calling ValidateFields().

Common situations: A hand-edited or generated .asmdef missing the name field, a malformed JSON, or a renamed asmdef that lost its name.

Related errors

• {reference} is not a GUID reference
• Both 'excludePlatforms' and 'includePlatforms' are set.
• Invalid Define Constraint: "{DefineConstraints[i]}" at line
• Platform name '{0}' not supported. Supported platform names:
• Assembly has duplicate references: {duplicateRefsString}

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/777555388f14290b. Report an issue: GitHub.