tensorflow/models · error · RuntimeError

Unknown replica context. The `get_replica_id` method relies

Error message

Unknown replica context. The `get_replica_id` method relies on TF 2.x tf.distribute API.

What it means

Error "Unknown replica context. The `get_replica_id` method relies on TF 2.x tf.distribute API." thrown in tensorflow/models.

Source

Thrown at official/modeling/tf_utils.py:223

  Args:
    losses: `Tensor` whose elements contain individual loss measurements.

  Returns:
    A scalar representing the mean of `losses`. If `num_present` is zero,
      then zero is returned.
  """
  total = tf.reduce_sum(losses)
  num_elements = tf.cast(tf.size(losses), dtype=losses.dtype)
  return tf.math.divide_no_nan(total, num_elements)


def get_replica_id():
  """Gets replica id depending on the environment."""
  context = tf.distribute.get_replica_context()
  if context is not None:
    return context.replica_id_in_sync_group
  else:
    raise RuntimeError("Unknown replica context. The `get_replica_id` method "
                       "relies on TF 2.x tf.distribute API.")


def cross_replica_concat(value, axis, name="cross_replica_concat"):
  """Concatenates the given `value` across (GPU/TPU) cores, along `axis`.

  In general, each core ("replica") will pass a
  replica-specific value as `value` (corresponding to some element of a
  data-parallel computation taking place across replicas).

  The resulting concatenated `Tensor` will have the same shape as `value` for
  all dimensions except `axis`, where it will be larger by a factor of the
  number of replicas. It will also have the same `dtype` as `value`.

  The position of a given replica's `value` within the resulting concatenation
  is determined by that replica's replica ID. For
  example:

View on GitHub (pinned to e006f5f0d5)

When it happens

Trigger: Thrown at official/modeling/tf_utils.py:223 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of tensorflow/models@e006f5f0d5 (2026-08-24). Data as JSON: /api/errors/fc0c393c8e5d328e. Report an issue: GitHub.