HandyOrg/HandyControl · error · ArgumentException

The type of this parameter does not support a required…

Error message

The type of this parameter does not support a required interface

What it means

Verify.TypeSupportsInterface checks that a Type argument implements a required interface using type.GetInterface(interfaceType.Name). It throws ArgumentException when the type does not expose an interface with the given name. Both arguments must be non-null (they are verified first).

Solutions

1. Implement the required interface on the type, or pass a different type that implements it
2. Check beforehand with typeof(IRequired).IsAssignableFrom(type)
3. Verify the interface name matches exactly — GetInterface matches by name

Example fix

// before
api.Check(typeof(MyClass), typeof(ICommand), "type"); // MyClass doesn't implement ICommand
// after
public class MyClass : ICommand { /* implement members */ }
// or guard:
if (typeof(ICommand).IsAssignableFrom(typeof(MyClass))) api.Check(typeof(MyClass), typeof(ICommand), "type");

if (type == null) throw new ArgumentNullException(nameof(type));
if (!interfaceType.IsAssignableFrom(type)) throw new ArgumentException($"{type} does not implement {interfaceType}", nameof(type));

bool Implements(Type t, Type i) => t != null && i != null && i.IsAssignableFrom(t);

try { api.Call(type); } catch (ArgumentException ex) when (ex.Message.Contains("required interface")) { /* fall back to a compatible type */ }

When it happens

Trigger: Passing a concrete Type (e.g. typeof(MyClass)) to an API expecting an implementer of a specific interface (e.g. ICommand or IWindowChrome), where the class does not implement it.

Common situations: Refactoring renames an interface or drops an implementation; passing a base class that lacks the interface that derived classes implement; type confusion between similarly named interfaces.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• The parameter must implement interface
• ExceptionStringTable.EventTriggerCannotFindEventNameExceptio…
• ExceptionStringTable.EventTriggerBaseInvalidEventExceptionMe…

AI-assisted analysis of HandyOrg/HandyControl@2c0875ebd6 (2026-09-14). Data as JSON: /api/errors/9118a6a4e0b4e0e2. Report an issue: GitHub.

Appendix: source

Thrown at src/Shared/Microsoft.Windows.Shell/Standard/Verify.cs:206

    [DebuggerStepThrough]
    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static void BoundedDoubleInc(double lowerBoundInclusive, double value, double upperBoundInclusive, string message, string parameter)
    {
        if (value < lowerBoundInclusive || value > upperBoundInclusive)
        {
            throw new ArgumentException(message, parameter);
        }
    }

    [DebuggerStepThrough]
    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    public static void TypeSupportsInterface(Type type, Type interfaceType, string parameterName)
    {
        Verify.IsNotNull<Type>(type, "type");
        Verify.IsNotNull<Type>(interfaceType, "interfaceType");
        if (type.GetInterface(interfaceType.Name) == null)
        {
            throw new ArgumentException("The type of this parameter does not support a required interface", parameterName);
        }
    }

    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
    [DebuggerStepThrough]
    public static void FileExists(string filePath, string parameterName)
    {
        Verify.IsNeitherNullNorEmpty(filePath, parameterName);
        if (!File.Exists(filePath))
        {
            throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, "No file exists at \"{0}\"", new object[]
            {
                filePath
            }), parameterName);
        }
    }

    [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]

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