microsoft/semantic-kernel · error · KernelException

Could not load type '{assemblyQualifiedTypeName}'.

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.

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)

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 '{stepInfo.InnerStepDotne
• Unable to create inner step type from assembly qualified nam
• Type '{stepStateType.Value}' could not be resolved to a vali
• Unable to deserialize KernelProcessEvent queue.
• Unable to deserialize ProcessEvent queue.

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