Unity-Technologies/UnityCsReference · error · ArgumentException

scriptPaths cannot be null or empty

Error message

scriptPaths cannot be null or empty

What it means

ArgumentException from the AssemblyBuilder constructor: the scriptPaths params array must be non-null and non-empty. The builder cannot compile with zero source files.

Source

Thrown at Editor/Mono/Scripting/ScriptCompilation/AssemblyBuilder.cs:74

        public string[] defaultDefines => GetDefaultDefines(EditorCompilationInterface.Instance);

        private class BeeScriptCompilationState
        {
            public ScriptAssembly[] assemblies;
            public ActiveBuild ActiveBuild;
            public EditorCompilation editorCompilation;
            public bool finishedCompiling;
        }
        private BeeScriptCompilationState activeBeeBuild;


        public AssemblyBuilder(string assemblyPath, params string[] scriptPaths)
        {
            if (string.IsNullOrEmpty(assemblyPath))
                throw new ArgumentException("assemblyPath cannot be null or empty");

            if (scriptPaths == null || scriptPaths.Length == 0)
                throw new ArgumentException("scriptPaths cannot be null or empty");

            this.scriptPaths = scriptPaths;
            this.assemblyPath = assemblyPath;

            compilerOptions = new ScriptCompilerOptions();
            flags = AssemblyBuilderFlags.None;
            referencesOptions = ReferencesOptions.None;
            buildTargetGroup = EditorUserBuildSettings.activeBuildTargetGroup;
            buildTarget = EditorUserBuildSettings.activeBuildTarget;
        }

        public bool Build()
        {
            return Build(EditorCompilationInterface.Instance);
        }

        internal bool Build(EditorCompilation editorCompilation)
        {

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Ensure at least one source file is collected before constructing the builder.
2. Null/length-check the scriptPaths array at the call site.

Example fix

// before
var b = new AssemblyBuilder(path, scripts);
// after
if (scripts == null || scripts.Length == 0) throw new ArgumentException("No scripts to compile", nameof(scripts));
var b = new AssemblyBuilder(path, scripts);

if (scriptPaths == null || scriptPaths.Length == 0)
    throw new ArgumentException("At least one script path is required", nameof(scriptPaths));

static bool HasScripts(string[] paths) => paths != null && paths.Length > 0;

try { var b = new AssemblyBuilder(assemblyPath, scripts); }
catch (ArgumentException ex) when (ex.Message.Contains("scriptPaths"))
{ /* collect actual source files and retry */ }

When it happens

Trigger: Constructing new AssemblyBuilder(path) with no script files, or passing a null array / empty array as scriptPaths.

Common situations: Building an assembly from a glob that matched nothing, or omitting the script paths argument.

Related errors

• assemblyPath cannot be null or empty
• Invalid argument {0} provided.
• {reference} is not a GUID reference
• Cannot start AssemblyBuilder with status {0}. Expected {1}
• targetCacheSize should be >= 0, got {targetCacheSize}

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/c22e2fc4c7d57703. Report an issue: GitHub.