AvaloniaUI/Avalonia · error · NotSupportedException

Property {Name} doesn't have a getter

Error message

Property {Name} doesn't have a getter

What it means

ClrPropertyInfo wraps a CLR property's getter and setter delegates. Get() throws NotSupportedException when the property was constructed with a null getter, i.e. the property is write-only (set accessor only). Avalonia binds by reading the property, so a write-only property cannot supply a value.

Source

Thrown at src/Avalonia.Base/Data/Core/ClrPropertyInfo.cs:25

    {
        private readonly Func<object, object?>? _getter;
        private readonly Action<object, object?>? _setter;

        public ClrPropertyInfo(string name, Func<object, object?>? getter, Action<object, object?>? setter, Type propertyType)
        {
            _getter = getter;
            _setter = setter;
            PropertyType = propertyType;
            Name = name;
        }

        public string Name { get; }
        public Type PropertyType { get; }

        public object? Get(object target)
        {
            if (_getter == null)
                throw new NotSupportedException("Property " + Name + " doesn't have a getter");
            return _getter(target);
        }

        public void Set(object target, object? value)
        {
            if (_setter == null)
                throw new NotSupportedException("Property " + Name + " doesn't have a setter");
            _setter(target, value);
        }

        public bool CanSet => _setter != null;
        public bool CanGet => _getter != null;
    }

    public class ReflectionClrPropertyInfo : ClrPropertyInfo
    {
        private static Action<object, object?>? CreateSetter(PropertyInfo info)
            => info.SetMethod is { } setMethod ?

View on GitHub (pinned to 11c5427268)

Solutions

1. Add a getter to the bound property (`public int X { get; set; }`).
2. Repoint the binding to a different property that is readable.
3. If using OneWayToSource only, ensure the binding direction is actually source-bound and you never read the target property.

Example fix

// before
public string Secret { set; }
<TextBlock Text="{Binding Secret}" />
// after
public string Secret { get; set; }

// Check CanGet before reading via ClrPropertyInfo.
if (propertyInfo is ClrPropertyInfo clr && !clr.CanGet)
    throw new InvalidOperationException($"{clr.Name} is write-only and cannot be read.");
var value = propertyInfo.Get(target);

static bool IsReadable(ClrPropertyInfo p) => p.CanGet;

try { return propertyInfo.Get(target); }
catch (NotSupportedException) { /* property has no getter */ return AvaloniaProperty.UnsetValue; }

When it happens

Trigger: Binding (reading direction) to a CLR property that only has a setter. Occurs when reflection or an explicit ClrPropertyInfo is created from a write-only member and then the binding engine calls Get().

Common situations: Binding a control to a viewmodel property declared as `public int X { set; }`; password-style write-only fields; refactoring a property to remove its getter while a binding still targets it.

Related errors

• Property {Name} doesn't have a setter
• Could not convert list index '{i}' of type '{argument}' to '
• Invalid method handle
• Unexpected null returned from Type.GetTypeFromHandle in Meth
• Two way bindings are not supported with a string format

AI-assisted analysis of AvaloniaUI/Avalonia@11c5427268 (2026-08-13). Data as JSON: /api/errors/b8334eb3ed7675de. Report an issue: GitHub.