langflow-ai/langflow · error · AttributeError

module '{self.__name__}' has no attribute '{name}'

Error message

module '{self.__name__}' has no attribute '{name}'

What it means

The lazy compat shim in langflow/__init__.py raises a plain AttributeError ('module ... has no attribute ...') when the forwarded attribute does not exist on the underlying lfx module. This mirrors normal Python semantics so hasattr() and try/except AttributeError keep working through the shim. It almost always means the symbol was renamed or moved during the langflow->lfx migration, not that the shim is broken.

Source

Thrown at src/backend/base/langflow/__init__.py:141

    def _get_lfx_module(self):
        """Lazily import and cache the lfx module."""
        if self._lfx_module is None:
            try:
                self._lfx_module = importlib.import_module(self._lfx_module_name)
            except ImportError as e:
                msg = f"Cannot import {self._lfx_module_name} for backwards compatibility with {self.__name__}"
                raise ImportError(msg) from e
        return self._lfx_module

    def __getattr__(self, name: str) -> Any:
        """Forward attribute access to the lfx module with caching."""
        lfx_module = self._get_lfx_module()
        try:
            attr = getattr(lfx_module, name)
        except AttributeError as e:
            msg = f"module '{self.__name__}' has no attribute '{name}'"
            raise AttributeError(msg) from e
        else:
            # Cache the attribute in our __dict__ for faster subsequent access
            setattr(self, name, attr)
            return attr

    def __dir__(self):
        """Return directory of the lfx module."""
        try:
            lfx_module = self._get_lfx_module()
            return dir(lfx_module)
        except ImportError:
            return []


def _setup_compatibility_modules():
    """Set up comprehensive compatibility modules for langflow.base imports."""
    # First, set up the base attribute on this module (langflow)
    current_module = sys.modules[__name__]

View on GitHub (pinned to 976ec789d2)

Solutions

1. Check what the lfx module actually exports: 'uv run python -c "import lfx; print([n for n in dir(lfx) if 'Chat' in n])"' and use the current name.
2. Search the repo for the new location: the symbol likely moved to lfx (grep for 'class <Symbol>' under src/lfx or src/backend).
3. If you maintain the shim mapping, add the missing re-export explicitly rather than relying on forwarding.
4. Pin to the langflow version whose API your code was written against until you migrate names.

Example fix

# before
from langflow import ChatInput  # AttributeError: module 'langflow' has no attribute 'ChatInput'
# after: use the current lfx name
from lfx.chat import ChatInput

import langflow
name = "ChatInput"
has_it = hasattr(langflow, name)  # goes through the shim's __getattr__ safely

def has_langflow_symbol(mod, name: str) -> bool:
    """True if the lazy compat shim can resolve the symbol."""
    return hasattr(mod, name)

try:
    Symbol = langflow.ChatInput
except AttributeError as e:
    raise NotImplementedError(
        f"{e}: symbol was renamed/moved in the lfx migration — import from lfx directly"
    ) from e

When it happens

Trigger: Accessing langflow.SomeSymbol where SomeSymbol exists neither in the legacy package's __dict__ nor on the lfx module the shim forwards to; using a symbol that was renamed/removed in the current lfx version.

Common situations: Upgrading across the langflow->lfx code move where a class or function was renamed (e.g. component base classes); stale custom code referencing pre-migration names; typo'd attribute that only fails at runtime due to lazy forwarding.

Related errors

• Cannot import {self._lfx_module_name} for backwards compatib
• The '{provider}' components moved to the 'lfx-bundles' distr
• Could not import {attr_name!r} from {__name__!r}: {e}
• Could not load flow module: {flow_path}
• Error loading flow module: {e}

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/8a54918a4ec0cfb2. Report an issue: GitHub.