aspnetboilerplate/aspnetboilerplate · error · ArgumentException

Given item is not type of

Error message

Given item is not type of 

What it means

TypeList<TBaseType> only accepts types assignable to TBaseType. Its private CheckType method verifies item via typeof(TBaseType).IsAssignableFrom(item) and throws ArgumentException "Given item is not type of <TBaseType.AssemblyQualifiedName>" when the check fails. This keeps the typed list type-safe at runtime for dynamically supplied types.

Solutions

1. Verify every type added inherits from or implements TBaseType
2. Add a compile-time constraint (where T : TBaseType) or unit test over the scanned assembly
3. Filter scanned types with typeof(TBaseType).IsAssignableFrom(t) before adding
4. Catch ArgumentException and log the offending type instead of failing the whole registration

Example fix

// before
var types = Assembly.GetExecutingAssembly().GetTypes();
foreach (var t in types) typeList.Add(t);
// after
foreach (var t in Assembly.GetExecutingAssembly().GetTypes().Where(x => typeof(IMyHandler).IsAssignableFrom(x) && !x.IsAbstract))
    typeList.Add(t);

if (!typeof(TBaseType).GetTypeInfo().IsAssignableFrom(itemType)) throw new ArgumentException($"{itemType} is not assignable to {typeof(TBaseType)}");

bool IsCompatible(Type t) => typeof(TBaseType).GetTypeInfo().IsAssignableFrom(t);

try { typeList.Add(itemType); } catch (ArgumentException ex) when (ex.Message.StartsWith("Given item is not type of")) { /* log and skip type */ }

When it happens

Trigger: Calling typeList.Add(someType) where someType does not inherit from/implement TBaseType — e.g. adding typeof(string) to a TypeList<IMyInterface>, or adding a derived class after the base contract changed.

Common situations: Plugin/convention-based registration scanning assemblies and adding wrong types; refactoring a class so it no longer implements the base interface while registration code still references it; assembly-loading picking up wrong version.

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.

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AI-assisted analysis of aspnetboilerplate/aspnetboilerplate@2323c13a15 (2026-09-08). Data as JSON: /api/errors/04fc61bfbb365ef3. Report an issue: GitHub.

Appendix: source

Thrown at src/Abp/Collections/TypeList.cs:150

            _typeList.CopyTo(array, arrayIndex);
        }

        /// <inheritdoc/>
        public IEnumerator<Type> GetEnumerator()
        {
            return _typeList.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return _typeList.GetEnumerator();
        }

        private static void CheckType(Type item)
        {
            if (!typeof(TBaseType).GetTypeInfo().IsAssignableFrom(item))
            {
                throw new ArgumentException("Given item is not type of " + typeof(TBaseType).AssemblyQualifiedName, "item");
            }
        }
    }
}

View on GitHub (pinned to 2323c13a15)