Unity-Technologies/UnityCsReference · error · ArgumentException

No valid types in required type list

Error message

No valid types in required type list

What it means

Thrown by the internal RequiredTypeList constructor (used by ObjectField/ObjectSelector) when, after processing every input required type plus the type derivable from the SerializedProperty, there are zero displayable types. The list adds a type only if it can resolve a non-null Type from either the explicit arguments or the property's PPtr name; if none resolve, the constructor refuses to build an empty selector.

Source

Thrown at Editor/Mono/EditorGUI.RequiredTypeList.cs:61

        public RequiredTypeList(IEnumerable<Type> requiredTypes, SerializedProperty property)
        {
            m_Property = property;

            foreach(var type in requiredTypes)
            {
                if (type is { IsInterface: true })
                {
                    foreach (var implementedType in TypeCache.GetTypesDerivedFrom(type))
                    {
                        AddType(implementedType);
                    }
                }
                else
                {
                    AddType(type);
                }

                if (type != null)
                    m_DisplayTypes.Add(type);
            }

            if (m_TypeFromProperty != null)
                m_DisplayTypes.Add(m_TypeFromProperty);

            if (m_DisplayTypes.Count == 0)
                throw new ArgumentException("No valid types in required type list");
        }

View on GitHub (pinned to 225b0fbdb5)

Solutions

1. Pass at least one concrete, non-null Type (e.g. typeof(UnityEngine.Object) or your ScriptableObject subclass) in the required types list.
2. Ensure the SerializedProperty passed actually resolves a field info (ScriptAttributeUtility.GetFieldInfoFromProperty succeeds) so m_TypeFromProperty is populated.
3. If using a built-in type, confirm its PPtr name in the property string matches a TypeCache-discoverable UnityEngine.Object type.
4. Guard your ObjectField call by validating requiredTypes.Any(t => t != null) before invoking.

Example fix

// before
EditorGUI.ObjectField(rect, prop, null); // null required types, prop can't resolve

// after
EditorGUI.ObjectField(rect, prop, typeof(MyScriptableObject));

if (requiredTypes == null || !requiredTypes.Any(t => t != null)) { if (prop == null) { Debug.LogError("ObjectField needs a Type or a resolvable property"); return; } }

static bool CanBuildRequiredTypeList(IEnumerable<Type> types, SerializedProperty prop) => types != null && types.Any(t => t != null) || (prop != null && ScriptAttributeUtility.GetFieldInfoFromProperty(prop, out _) != null);

When it happens

Trigger: Calling EditorGUI.ObjectField (or ObjectSelector.Show) with a requiredTypes collection containing only null entries AND a SerializedProperty whose type string does not match any UnityEngine.Object-derived type via the PPtr<...> regex match. Also when a custom property drawer passes an empty or all-null type array.

Common situations: Custom PropertyDrawer that calls ObjectField with null types assuming the property will fill them in, but the property references a built-in type whose name the regex cannot extract. Editor scripts building an object picker for a non-serialized pseudo-property. Mismatch between a SerializedProperty.type string and the actual loaded assembly types.

Related errors

• type
• Parameter selected must be of type System.Enum
• Parameter enumValue must be of type System.Enum
• Unsupported enum base type for {0}
• Specified enumType must be System.Enum

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/1166987cbea50b62. Report an issue: GitHub.