boto/boto3 · error · ResourceLoadException

{parent.__class__.__name__} has no load method!

Error message

{parent.__class__.__name__} has no load method!

What it means

Raised by get_data_member() in boto3/resources/params.py when a request-parameter or identifier path requires data from a parent resource, meta.data is None, and the parent has no load method. This is the same root cause as error 16 but triggered internally during create_request_parameters — i.e. when building the arguments for a resource action that references a 'data' source and the parent was never hydrated.

Source

Thrown at boto3/resources/params.py:44

    Get a data member from a parent using a JMESPath search query,
    loading the parent if required. If the parent cannot be loaded
    and no data is present then an exception is raised.

    :type parent: ServiceResource
    :param parent: The resource instance to which contains data we
                   are interested in.
    :type path: string
    :param path: The JMESPath expression to query
    :raises ResourceLoadException: When no data is present and the
                                   resource cannot be loaded.
    :returns: The queried data or ``None``.
    """
    # Ensure the parent has its data loaded, if possible.
    if parent.meta.data is None:
        if hasattr(parent, 'load'):
            parent.load()
        else:
            raise ResourceLoadException(
                f'{parent.__class__.__name__} has no load method!'
            )

    return jmespath.search(path, parent.meta.data)


def create_request_parameters(parent, request_model, params=None, index=None):
    """
    Handle request parameters that can be filled in from identifiers,
    resource data members or constants.

    By passing ``params``, you can invoke this method multiple times and
    build up a parameter dict over time, which is particularly useful
    for reverse JMESPath expressions that append to lists.

    :type parent: ServiceResource
    :param parent: The resource instance to which this action is attached.
    :type request_model: :py:class:`~boto3.resources.model.Request`

View on GitHub (pinned to c7b4afac23)

Solutions

1. Hydrate the parent before invoking the action: parent.load() if available, or perform a describing call first.
2. Construct the parent from a response that already includes data (e.g. via a list/collection).
3. Fall back to the low-level client to supply the needed parameter explicitly.

Example fix

# before
parent = some_resource(id='x')
parent.related_action()  # action needs parent.data_field, no load -> error

# after
parent = some_resource(id='x')
if hasattr(parent, 'load'):
    parent.load()
parent.related_action()

def ensure_loaded(resource):
    if resource.meta.data is None and hasattr(resource, 'load'):
        resource.load()
    return resource

def can_load(resource) -> bool:
    return hasattr(resource, 'load') or resource.meta.data is not None

from boto3.exceptions import ResourceLoadException
try:
    parent.related_action()
except ResourceLoadException:
    # hydrate or use low-level client
    parent.meta.client.some_api_call(...)

When it happens

Trigger: Calling an action on a resource whose request model references a data member of the parent, when the parent has no load action and no cached data. E.g. invoking a relation/action that needs parent.some_field where parent was built from identifiers only.

Common situations: Chaining resource actions on identifier-only parent resources that lack a load method; service-model definitions where a data member is referenced but the resource cannot self-load.

Related errors

• {self.__class__.__name__} has no load method
• Unknown keyword argument: {name}
• Required parameter {identifier} not set
• Unsupported source type: {source}
• Unsupported source type: {source}

AI-assisted analysis of boto/boto3@c7b4afac23 (2026-08-04). Data as JSON: /data/errors/7cce716294f7ee5c.json. Report an issue: GitHub.