jax-ml/jax · error · AttributeError

module '{package_name}' has no attribute '{name}'

Error message

module '{package_name}' has no attribute '{name}'

What it means

AttributeError from the PEP 562 __getattr__ installed by lazy_loader.attach: the requested attribute is not one of the declared lazy submodules of the package, so after failing the submodule lookup it raises. This is the standard 'module has no attribute' error for lazily loaded JAX subpackages like jax.lib or jax.experimental.

Source

Thrown at jax/_src/lazy_loader.py:52

  Raises:
    RuntimeError: If the ``__name__`` of the caller cannot be determined.
  """
  owner_name = sys._getframe(1).f_globals.get("__name__")
  if owner_name is None:
    raise RuntimeError("Cannot determine the ``__name__`` of the caller.")

  __all__ = list(submodules)

  def __getattr__(name: str) -> Any:
    if name in submodules:
      value = importlib.import_module(f"{package_name}.{name}")
      # Update module-level globals to avoid calling ``__getattr__`` again
      # for this ``name``.
      assert owner_name is not None  # pyrefly#40
      setattr(sys.modules[owner_name], name, value)
      return value
    raise AttributeError(f"module '{package_name}' has no attribute '{name}'")

  def __dir__() -> list[str]:
    return __all__

  return __getattr__, __dir__, __all__

View on GitHub (pinned to 1e1c6a8fc0)

Solutions

1. Check the attribute spelling against the JAX version's module list (dir(jax.lib))
2. Import the public API instead (e.g. jax.Array, jax.device_get) rather than jax.lib internals
3. Pin or match the JAX version your dependency was written for
4. Use getattr(module, name, None) if the attribute is optional across versions

Example fix

# before
from jax.lib import xla_bridge  # typo / renamed

# after
import jax
client = jax.lib.xla_client.get_default_client()

import jax.lib
name = 'xla_client'
has = name in dir(jax.lib)

def has_attr(pkg, name):
    return name in dir(pkg)

try:
    obj = getattr(jax.lib, name)
except AttributeError:
    obj = None  # handle version without this submodule

When it happens

Trigger: Accessing jax.lib.<something> or similar lazily attached package where <something> is not in the attach(submodules=...) list — e.g. a typo (jax.lib.xla_client vs jax.lib.xla_extension), or a submodule removed/renamed in a JAX version.

Common situations: Upgrading JAX where internal modules were renamed (xla_client moves, jax.lib reorganization); typos in private/internal imports; code depending on jax._src or jax.lib internals that are not part of attach's submodule list.

Related errors

• {self.__class__.__name__} has no attribute {name}
• Cannot determine the ``__name__`` of the caller.
• numpy masked arrays are not supported as direct inputs to JA
• Python int {value} too large to convert to int64
• Python int {value} too large to convert to int32

AI-assisted analysis of jax-ml/jax@1e1c6a8fc0 (2026-08-27). Data as JSON: /api/errors/3d9a9368af65b6f7. Report an issue: GitHub.