elsa-workflows/elsa-core · error · InvalidOperationException

Type ' ' not found.

Error message

Type '{stringValue}' not found.

What it means

TypeTypeConverter converts a string (from e.g. TypeConverter-based binding or property grids) into a Type. It first tries the TypeAliasRegistry, then Type.GetType; if both fail it throws InvalidOperationException because the requested type cannot be located.

Solutions

1. Use the assembly-qualified type name (e.g. "My.Namespace.MyType, My.Assembly, Version=...")
2. Register the alias with the TypeAliasRegistry so the short name resolves
3. Ensure the assembly containing the type is loaded before conversion
4. Fix typos in the namespace/type name

Example fix

// before
var t = (Type)TypeDescriptor.GetConverter(typeof(Type)).ConvertFrom("MyActivity");
// after
var t = (Type)TypeDescriptor.GetConverter(typeof(Type)).ConvertFrom("MyApp.Activities.MyActivity, MyApp");

var resolved = TypeAliasRegistry.GetType(name) ?? Type.GetType(name);
if (resolved is null) throw new ArgumentException($"Type '{name}' is not resolvable.", nameof(name));

bool IsResolvableType(string name) => TypeAliasRegistry.GetType(name) is not null || Type.GetType(name, throwOnError: false) is not null;

try { return (Type)converter.ConvertFrom(name); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("Type '") && ex.Message.EndsWith("' not found."))
{ logger.LogWarning("Unknown type name {Name}", name); return null; }

When it happens

Trigger: Calling TypeDescriptor.GetConverter(typeof(Type)).ConvertFrom("Some.Type.Name") (or assigning a string to a Type property through such a converter) with a string that is neither a registered type alias nor an assembly-qualified type name resolvable by Type.GetType.

Common situations: Passing a short type name like "MyActivity" instead of an assembly-qualified name; typo in namespace; the assembly containing the type is not loaded into the AppDomain; alias not registered in TypeAliasRegistry.

Related errors

• Type not found.
• Type does not expose an Add method for .
• Value cannot be null. (Parameter 'type')
• Multiple Invoke methods were found. Use either Invoke or…
• No Invoke methods were found. Use either Invoke or…

AI-assisted analysis of elsa-workflows/elsa-core@fe9217bdfa (2026-09-13). Data as JSON: /api/errors/fbcc44184445a448. Report an issue: GitHub.

Appendix: source

Thrown at src/modules/Elsa.Common/Serialization/TypeTypeConverter.cs:21

using JetBrains.Annotations;

namespace Elsa.Common.Serialization;

[PublicAPI]
public class TypeTypeConverter : TypeConverter
{
    public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
    {
        return sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
    }

    public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
    {
        if (value is string stringValue)
        {
            if (TypeAliasRegistry.GetType(stringValue) is { } type)
                return type;
            return Type.GetType(stringValue) ?? throw new InvalidOperationException($"Type '{stringValue}' not found.");
        }
        return base.ConvertFrom(context, culture, value);
    }

    public override bool CanConvertTo(ITypeDescriptorContext? context, Type? destinationType)
    {
        return destinationType == typeof(string) || base.CanConvertTo(context, destinationType);
    }

    public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
    {
        if (destinationType == typeof(string) && value is Type type)
        {
            if (TypeAliasRegistry.TypeAliases.FirstOrDefault(x => x.Value == type).Key is { } alias)
                return alias;
            return type.AssemblyQualifiedName;
        }
        return base.ConvertTo(context, culture, value, destinationType);

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