boto/boto3 · error · ResourceLoadException

{self.__class__.__name__} has no load method

Error message

{self.__class__.__name__} has no load method

What it means

Raised by the auto-loaded property created in _create_autoload_property when meta.data is None (the resource has not been hydrated) and the resource class has no load method. The property loader checks hasattr(self, 'load'); if absent, it cannot fetch data to satisfy the attribute access, so ResourceLoadException is raised. Not every resource model defines a load action; those that do not cannot lazy-load attributes.

Source

Thrown at boto3/resources/factory.py:383

        snake_cased,
        member_model,
        service_context,
    ):
        """
        Creates a new property on the resource to lazy-load its value
        via the resource's ``load`` method (if it exists).
        """

        # The property loader will check to see if this resource has already
        # been loaded and return the cached value if possible. If not, then
        # it first checks to see if it CAN be loaded (raise if not), then
        # calls the load before returning the value.
        def property_loader(self):
            if self.meta.data is None:
                if hasattr(self, 'load'):
                    self.load()
                else:
                    raise ResourceLoadException(
                        f'{self.__class__.__name__} has no load method'
                    )

            return self.meta.data.get(name)

        property_loader.__name__ = str(snake_cased)
        property_loader.__doc__ = docstring.AttributeDocstring(
            service_name=service_context.service_name,
            resource_name=resource_name,
            attr_name=snake_cased,
            event_emitter=factory_self._emitter,
            attr_model=member_model,
            include_signature=False,
        )

        return property(property_loader)

    def _create_waiter(

View on GitHub (pinned to c7b4afac23)

Solutions

1. Hydrate the resource explicitly by performing a describing action (e.g. obj = bucket.Object('k'); obj.get()) so meta.data is populated.
2. Check hasattr(resource, 'load') before accessing data attributes.
3. Use the low-level client to fetch the data if the resource has no load action.

Example fix

# before
obj = s3.Object('mybucket', 'k')
print(obj.last_modified)  # no data, no load method -> error

# after
obj = s3.Object('mybucket', 'k')
obj.load()  # or obj.get() then re-access
print(obj.last_modified)
# guard:
if hasattr(obj, 'load'):
    obj.load()

def safe_get_attr(resource, attr_name):
    if resource.meta.data is None:
        if hasattr(resource, 'load'):
            resource.load()
        else:
            return None
    return getattr(resource, attr_name, None)

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

from boto3.exceptions import ResourceLoadException
try:
    val = resource.some_attribute
except ResourceLoadException:
    # resource has no load method; fetch via client or skip
    val = resource.meta.client.get_object(Bucket=..., Key=...)

When it happens

Trigger: Accessing a data attribute (e.g. obj.last_modified) on a resource that was constructed without data and whose model has no load action. E.g. some S3 Object sub-resources or relation-only resources.

Common situations: Constructing a resource from identifiers only and then reading a data field; accessing attributes on a resource type that the service model marks as having no load; calling .load() implicitly via property access after a failed/empty response.

Related errors

• {parent.__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/510fdf9b970ef63c.json. Report an issue: GitHub.