microsoft/semantic-kernel · error · KernelException

Could not load type ' '.

Error message

Could not load type '{assemblyQualifiedTypeName}'.

What it means

Thrown by TypeInfo.ConvertValue when Type.GetType cannot resolve the provided assembly-qualified type name to a .NET Type. The JsonElement value cannot be deserialized without knowing its target type.

Solutions

1. Deploy the assembly containing the persisted value's type to the Dapr actor host.
2. Verify the assembly-qualified name is complete and correct (assembly, version, PublicKeyToken).
3. If the type moved, add TypeForwardedFrom or load the appropriate AssemblyLoadContext.
4. Disable aggressive trimming/AOT for assemblies holding persisted value types.

var valueType = Type.GetType(assemblyQualifiedTypeName);
if (valueType is null)
    throw new InvalidOperationException($"Type '{assemblyQualifiedTypeName}' is not loadable; deploy its assembly.");

public static bool IsTypeLoadable(string assemblyQualifiedTypeName) =>
    Type.GetType(assemblyQualifiedTypeName) is not null;

try
{
    var restored = TypeInfo.ConvertValue(typeName, value);
}
catch (KernelException ex) when (ex.Message.Contains("Could not load type"))
{
    _logger.LogError(ex, "Persisted value type assembly is missing from the host.");
    throw;
}

When it happens

Trigger: ConvertValue resolves Type.GetType(assemblyQualifiedTypeName); a null result means the type (or its assembly) is not available to the current runtime.

Common situations: The type's assembly is not loaded by the actor host, the assembly-qualified name is malformed or truncated, the type was renamed/removed in a newer version, or trimming removed the type metadata.

Related errors

• Could not load the inner step type
• Unable to create inner step type from assembly qualified…
• Data persisted without type information.
• Type ' ' could not be resolved to a valid…
• Unable to deserialize KernelProcessEvent queue.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/a539e865f3a4108a. Report an issue: GitHub.

Appendix: source

Thrown at dotnet/src/Experimental/Process.Runtime.Dapr/Serialization/TypeInfo.cs:44

    /// Restore the object's type from the provided assembly qualified type-name, but
    /// only if it is a <see cref="JsonElement"/>. Otherwise, return the original value.
    /// </summary>
    public static object? ConvertValue(string? assemblyQualifiedTypeName, object? value)
    {
        if (value == null || value.GetType() != typeof(JsonElement))
        {
            return value;
        }

        if (assemblyQualifiedTypeName == null)
        {
            throw new KernelException("Data persisted without type information.");
        }

        Type? valueType = Type.GetType(assemblyQualifiedTypeName);
        if (valueType is null)
        {
            throw new KernelException($"Could not load type '{assemblyQualifiedTypeName}'.");
        }

        return ((JsonElement)value).Deserialize(valueType);
    }
}

View on GitHub (pinned to c028a0c7dc)