diff --git a/vmoe/checkpoints/base_test.py b/vmoe/checkpoints/base_test.py
index e88e72d..8e6bf40 100644
--- a/vmoe/checkpoints/base_test.py
+++ b/vmoe/checkpoints/base_test.py
@@ -88,13 +88,15 @@ def test_save_and_restore_multiple_checkpoints(self):
     # Restore checkpoints without specifying the tree structure.
     restored_filepath_tree_map = base.restore_multiple_checkpoints(
         {key: None for key in filepath_tree_map})
-    jax.tree_map(np.testing.assert_array_equal, restored_filepath_tree_map,
-                 filepath_tree_map)
+    jax.tree_util.tree_map(np.testing.assert_array_equal,
+                           restored_filepath_tree_map,
+                           filepath_tree_map)
     # Restore checkpoints specifying the tree structure.
     restored_filepath_tree_map = base.restore_multiple_checkpoints(
-        jax.tree_structure(filepath_tree_map).unflatten([1, 2, 3, 4]))
-    jax.tree_map(np.testing.assert_array_equal, restored_filepath_tree_map,
-                 filepath_tree_map)
+        jax.tree_util.tree_structure(filepath_tree_map).unflatten([1, 2, 3, 4]))
+    jax.tree_util.tree_map(np.testing.assert_array_equal,
+                           restored_filepath_tree_map,
+                           filepath_tree_map)
     # Check that the bfloat16 is restored properly.
     self.assertEqual(
         restored_filepath_tree_map[workdir + '/checkpoint_2'].dtype,
diff --git a/vmoe/checkpoints/partitioned.py b/vmoe/checkpoints/partitioned.py
index b873a2b..99cf06d 100644
--- a/vmoe/checkpoints/partitioned.py
+++ b/vmoe/checkpoints/partitioned.py
@@ -404,7 +404,7 @@ def _replace_jax_with_numpy_in_lazy_array_chunks(
     for lst in lac.chunks.values():
       for arr, _, _ in lst:
         id_to_array[id(arr)] = arr
-  id_to_array = jax.tree_map(np.asarray, id_to_array)
+  id_to_array = jax.tree_util.tree_map(np.asarray, id_to_array)
   for lac in ckpt_shard_to_lazy_array_chunks.values():
     for i, lst in lac.chunks.items():
       lac.chunks[i] = [
diff --git a/vmoe/checkpoints/serialization.py b/vmoe/checkpoints/serialization.py
index 19bbc37..f5b6723 100644
--- a/vmoe/checkpoints/serialization.py
+++ b/vmoe/checkpoints/serialization.py
@@ -109,7 +109,7 @@ def msgpack_serialize(pytree: PyTree, in_place: bool = False) -> bytes:
     msgpack-encoded bytes of pytree.
   """
   if not in_place:
-    pytree = jax.tree_map(lambda x: x, pytree)
+    pytree = jax.tree_util.tree_map(lambda x: x, pytree)
   pytree = _np_convert_in_place(pytree)
   pytree = _chunk_array_leaves_in_place(pytree)
   return msgpack.packb(pytree, default=_msgpack_ext_pack, strict_types=True)
@@ -137,7 +137,8 @@ def to_bytes(target: PyTree) -> bytes:
 _ndarray_to_bytes = flax.serialization._ndarray_to_bytes
 _ndarray_from_bytes = flax.serialization._ndarray_from_bytes
 _np_convert_in_place = flax.serialization._np_convert_in_place
-_unchunk_array_leaves_in_place = flax.serialization._unchunk_array_leaves_in_place
+_unchunk_array_leaves_in_place = (
+    flax.serialization._unchunk_array_leaves_in_place)
 _MAX_CHUNK_SIZE = flax.serialization.MAX_CHUNK_SIZE
 # pylint: enable=protected-access
 
@@ -146,6 +147,7 @@ def to_bytes(target: PyTree) -> bytes:
 
 
 class _MsgpackExtType(enum.IntEnum):
+  # pylint: disable=invalid-name
   ndarray = 1
   native_complex = 2
   npscalar = 3
@@ -154,6 +156,7 @@ class _MsgpackExtType(enum.IntEnum):
   slice_nd = 6
   slice_nd_array = 7
   index_info = 8
+  # pylint: enable=invalid-name
 
 
 def _shaped_array_to_bytes(x: core.ShapedArray) -> bytes:
diff --git a/vmoe/data/pjit_utils.py b/vmoe/data/pjit_utils.py
index 6790aa2..0e674b6 100644
--- a/vmoe/data/pjit_utils.py
+++ b/vmoe/data/pjit_utils.py
@@ -107,7 +107,7 @@ def _to_global(x):
 
     def enqueue(n):
       for data in itertools.islice(iterator, n):
-        queue.append(jax.tree_map(_to_global, data))
+        queue.append(jax.tree_util.tree_map(_to_global, data))
 
     enqueue(size)
     while queue:
@@ -117,7 +117,7 @@ def enqueue(n):
     # If size is None, 0 or negative, simply create jax.Arrays without
     # prefetching.
     for data in iterator:
-      yield jax.tree_map(_to_global, data)
+      yield jax.tree_util.tree_map(_to_global, data)
 
 
 def put_to_devices(host_array: np.ndarray,
diff --git a/vmoe/evaluate/evaluator.py b/vmoe/evaluate/evaluator.py
index 61015f7..2ab4d7c 100644
--- a/vmoe/evaluate/evaluator.py
+++ b/vmoe/evaluate/evaluator.py
@@ -226,7 +226,7 @@ def evaluate_dataset(
   for batch in dataset:
     eval_state = eval_step_pjit(eval_state, params, batch['image'],
                                 batch['labels'], batch[VALID_KEY])
-  return jax.tree_map(lambda x: x.block_until_ready(), eval_state)
+  return jax.tree_util.tree_map(lambda x: x.block_until_ready(), eval_state)
 
 
 def evaluate_step(
diff --git a/vmoe/initialization/initialization.py b/vmoe/initialization/initialization.py
index 591a512..0e4984e 100644
--- a/vmoe/initialization/initialization.py
+++ b/vmoe/initialization/initialization.py
@@ -233,10 +233,11 @@ def initialize_from_vmoe(
   # each array read from the checkpoint.
   index = vmoe_checkpoint.restore_checkpoint(prefix + '.index')
   version = index.get('version', vmoe_checkpoint.Version.UNKNOWN)
-  shapes = jax.tree_map(lambda x: x.global_shape, index['index'])
+  shapes = jax.tree_util.tree_map(lambda x: x.global_shape, index['index'])
   if version == vmoe_checkpoint.Version.UNKNOWN:
-    if (jax.tree_structure(vmoe_serialization.to_state_dict(target)) !=
-        jax.tree_structure(shapes)):
+    target_state_dict = vmoe_serialization.to_state_dict(target)
+    if (jax.tree_util.tree_structure(target_state_dict) !=
+        jax.tree_util.tree_structure(shapes)):
       raise ValueError(
           'Initialization from V-MoE checkpoints created before 2022/06/22 '
           'is only possible when the structure of the checkpoint and target '
diff --git a/vmoe/moe.py b/vmoe/moe.py
index d6e963a..2992002 100644
--- a/vmoe/moe.py
+++ b/vmoe/moe.py
@@ -428,7 +428,7 @@ def wrapper(expert_fn: Callable[..., Any]):
 
     def transformed(scopes, dispatcher, *inputs):
       # Prepare inputs to be processed by each expert.
-      inputs = jax.tree_map(dispatcher.dispatch, inputs)
+      inputs = jax.tree_util.tree_map(dispatcher.dispatch, inputs)
       # Wrap the target with vmap, to pass different parameters and inputs to
       # each expert.
       outputs = flax.core.lift.vmap(
@@ -440,7 +440,7 @@ def transformed(scopes, dispatcher, *inputs):
       # Combine outputs.
       if has_aux:
         outputs, aux = outputs
-      outputs = jax.tree_map(dispatcher.combine, outputs)
+      outputs = jax.tree_util.tree_map(dispatcher.combine, outputs)
       return (outputs, aux) if has_aux else outputs
 
     return transformed
diff --git a/vmoe/moe_test.py b/vmoe/moe_test.py
index 3ff6d1a..8912847 100644
--- a/vmoe/moe_test.py
+++ b/vmoe/moe_test.py
@@ -491,7 +491,7 @@ def init(rng):
     # All parameters are partitioned across the first axis of the TPU mesh.
     # Thus, each group of devices in one "row" will share the same values for
     # all parameters.
-    param_partition_spec = jax.tree_map(
+    param_partition_spec = jax.tree_util.tree_map(
         lambda _: jax.sharding.PartitionSpec(('expert',)),
         jax.eval_shape(init, jax.random.PRNGKey(0)))
     init_pjit = pjit.pjit(
@@ -586,7 +586,7 @@ def __call__(self, x, w):
     data_axis_resources = PartitionSpec(('X', 'Y'))
     variables_axis_resources = flax.core.freeze({
         'params':
-            jax.tree_map(
+            jax.tree_util.tree_map(
                 lambda x: nn.partitioning.logical_to_mesh_axes(x, axis_rules),
                 nn.partitioning.get_axis_names(variables_shape['params_axes'])),
     })
diff --git a/vmoe/nn/external_test.py b/vmoe/nn/external_test.py
index 5c3bf65..25dc34f 100644
--- a/vmoe/nn/external_test.py
+++ b/vmoe/nn/external_test.py
@@ -57,16 +57,19 @@ def compute_grad(params):
 
       variables = model.init(jax.random.PRNGKey(0), x)
       params = variables['params']
+      grads = None
       for _ in range(2):
         grads = compute_grad(params)
-        params = jax.tree_map(lambda p, g: p - 0.01 * g, params, grads)
+        params = jax.tree_util.tree_map(
+            lambda p, g: p - 0.01 * g, params, grads)
 
       return grads
 
     x = jax.random.normal(jax.random.PRNGKey(0), (8, 64, 64, 3))
     grads = fn(x)
-    grads_norm = jax.tree_map(lambda x: jnp.linalg.norm(x.flatten()), grads)
-    zeros = jax.tree_map(jnp.zeros_like, grads_norm)
+    grads_norm = jax.tree_util.tree_map(
+        lambda x: jnp.linalg.norm(x.flatten()), grads)
+    zeros = jax.tree_util.tree_map(jnp.zeros_like, grads_norm)
     print(grads_norm)
     chex.assert_trees_all_equal_comparator(lambda x, y: x > y,
                                            '{} is not greater than {}'.format,
diff --git a/vmoe/nn/vit_moe_ensemble_test.py b/vmoe/nn/vit_moe_ensemble_test.py
index f3810c5..73099d8 100644
--- a/vmoe/nn/vit_moe_ensemble_test.py
+++ b/vmoe/nn/vit_moe_ensemble_test.py
@@ -43,7 +43,8 @@ def init(rngs, x):
 
     rngs = dict(params=jax.random.PRNGKey(0), gating=jax.random.PRNGKey(1))
     x = jax.random.normal(jax.random.PRNGKey(0), (16, 4, 4, 3))
-    shapes = jax.tree_map(lambda x: x.shape, jax.eval_shape(init, rngs, x))
+    shapes = jax.tree_util.tree_map(
+        lambda x: x.shape, jax.eval_shape(init, rngs, x))
     shapes = flax.core.unfreeze(shapes)
     expected_shapes = {
         'params': {
diff --git a/vmoe/nn/vit_moe_test.py b/vmoe/nn/vit_moe_test.py
index d5d0bce..6f52a6e 100644
--- a/vmoe/nn/vit_moe_test.py
+++ b/vmoe/nn/vit_moe_test.py
@@ -153,7 +153,7 @@ def init():
       x = jax.random.normal(jax.random.PRNGKey(0), (16, 4, 4, 3))
       return model.init(rngs, x)
 
-    shapes = jax.tree_map(
+    shapes = jax.tree_util.tree_map(
         lambda x: x.shape, flax.core.unfreeze(jax.eval_shape(init))
     )
     expected_shapes = {
@@ -237,8 +237,8 @@ def test_classifier(self, classifier, seq_length, params_subset):
     model = vit_moe.VisionTransformerMoe(**config)
     rngs = dict(params=jax.random.PRNGKey(0), gating=jax.random.PRNGKey(1))
     x = jax.ShapeDtypeStruct((16, 4, 4, 3), jax.numpy.float32)
-    shapes = jax.tree_map(lambda x: x.shape,
-                          jax.eval_shape(model.init, rngs, x))
+    shapes = jax.tree_util.tree_map(lambda x: x.shape,
+                                    jax.eval_shape(model.init, rngs, x))
     shapes = flax.core.unfreeze(shapes)
     self.assertDictEqual(shapes['params']['Encoder']['posembed_input'],
                          {'pos_embedding': (1, seq_length, 8)})
diff --git a/vmoe/projects/adversarial_attacks/attacks.py b/vmoe/projects/adversarial_attacks/attacks.py
index f3177d7..ddacfa1 100644
--- a/vmoe/projects/adversarial_attacks/attacks.py
+++ b/vmoe/projects/adversarial_attacks/attacks.py
@@ -120,7 +120,8 @@ def mask(a):
   num_changes = jnp.sum(y_m != y_0, dtype=jnp.int32)
   num_correct = jnp.stack([c_0.sum(), c_m.sum()], axis=0)
   sum_loss = jnp.stack([l_0.sum(), l_m.sum()], axis=0)
-  sum_iou_experts = jax.tree_map(sum_intersection_over_union, cw_0, cw_m)
+  sum_iou_experts = jax.tree_util.tree_map(
+      sum_intersection_over_union, cw_0, cw_m)
   new_attack_state = attack_state.update(
       rngs=new_rngs, num_images=num_images, num_changes=num_changes,
       num_correct=num_correct, sum_loss=sum_loss,
@@ -151,7 +152,8 @@ def stateless_attack_pgd(
   # If rngs are given, split them in num_updates + 1. The last one will be
   # returned at the end of this function, the others are used in each update.
   if rngs is not None:
-    rngs = jax.tree_map(lambda rng: jax.random.split(rng, num_updates +1), rngs)
+    rngs = jax.tree_util.tree_map(
+        lambda rng: jax.random.split(rng, num_updates +1), rngs)
   # This computes gradients of loss_fn w.r.t. the images.
   @jax.grad
   def compute_loss_grads(x, rngs):
@@ -160,13 +162,15 @@ def compute_loss_grads(x, rngs):
     return loss
   # Performs an adversarial update on the given images.
   def update(i, x_c):
-    rngs_c = jax.tree_map(lambda x: x[i], rngs) if rngs is not None else None
+    rngs_c = jax.tree_util.tree_map(
+        lambda x: x[i], rngs) if rngs is not None else None
     dx = compute_loss_grads(x_c, rngs_c)
     x_n = x_c + delta * jnp.sign(dx)
     return x_n
   # Performs num_updates on the original images.
   images = jax.lax.fori_loop(0, num_updates, update, images)
-  rngs = jax.tree_map(lambda x: x[-1], rngs) if rngs is not None else None
+  rngs = jax.tree_util.tree_map(
+      lambda x: x[-1], rngs) if rngs is not None else None
   return images, rngs
 
 
diff --git a/vmoe/projects/adversarial_attacks/lib.py b/vmoe/projects/adversarial_attacks/lib.py
index da5f3f3..9ecc99a 100644
--- a/vmoe/projects/adversarial_attacks/lib.py
+++ b/vmoe/projects/adversarial_attacks/lib.py
@@ -53,7 +53,7 @@ def __init__(self, filepath: str, transfer_every_steps: int = 1):
 
   def _transfer(self):
     for key, values in self._temp.items():
-      self._data[key].extend(jax.tree_map(np.asarray, values))
+      self._data[key].extend(jax.tree_util.tree_map(np.asarray, values))
       self._temp[key] = []
 
   @property
@@ -99,6 +99,7 @@ def run_pgd_attack(
     config: ml_collections.ConfigDict, workdir: str, mesh: Mesh,
     writer: metric_writers.MetricWriter):
   """Run PGD attack on an entire dataset, using a model from an XM experiment."""
+  del mesh
   # Setup dataset and get the global shape of the image array.
   dataset = get_dataset(config.dataset)
   element_spec: ArraySpecDict = dataset.element_spec  # pytype: disable=annotation-type-mismatch
@@ -141,8 +142,8 @@ def init_state():
     rngs = utils.make_rngs(rng_keys, config.get('seed', 0))
     return attacks.AttackState.create(
         max_updates=config.num_updates, router_keys=router_keys, rngs=rngs)
-  state_axis_resources = jax.tree_map(lambda _: PartitionSpec(),
-                                      jax.eval_shape(init_state))
+  state_axis_resources = jax.tree_util.tree_map(lambda _: PartitionSpec(),
+                                                jax.eval_shape(init_state))
   init_state_pjit = pjit.pjit(
       init_state, in_shardings=(), out_shardings=state_axis_resources
   )
@@ -203,7 +204,7 @@ def compute_loss_predict_correct_cw_fn(images, labels, rngs):
             **{f'cw_0/{k}': v for k, v in cw_0.items()},
             **{f'cw_m/{k}': v for k, v in cw_m.items()})
   # Copy state from device to CPU and convert to numpy arrays.
-  state = jax.tree_map(np.asarray, state)
+  state = jax.tree_util.tree_map(np.asarray, state)
   # Process with index=0 saves the PGD state (it's the same for all processes).
   if jax.process_index() == 0:
     state_filepath = os.path.join(workdir, 'pgd_state.npz')
diff --git a/vmoe/projects/adversarial_attacks/lib_test.py b/vmoe/projects/adversarial_attacks/lib_test.py
index 8f14bde..9eacf6c 100644
--- a/vmoe/projects/adversarial_attacks/lib_test.py
+++ b/vmoe/projects/adversarial_attacks/lib_test.py
@@ -61,8 +61,8 @@ def __call__(self, x):
   flax_module = ModelWithRouting()
   image_size = (batch_size, image_size, image_size, 3)
   variables = flax_module.init(jax.random.PRNGKey(0), np.zeros(image_size))
-  variables_axis_resources = jax.tree_map(lambda _: lib.PartitionSpec(),
-                                          variables)
+  variables_axis_resources = jax.tree_util.tree_map(
+      lambda _: lib.PartitionSpec(), variables)
   router_keys = {'router/__call__'}
   loss_fn = lambda a, b, _: optax.softmax_cross_entropy(a, b)
   return (flax_module, variables, variables_axis_resources, loss_fn,
@@ -82,8 +82,8 @@ def __call__(self, x):
   flax_module = ModelWithoutRouting()
   image_size = (batch_size, image_size, image_size, 3)
   variables = flax_module.init(jax.random.PRNGKey(0), np.zeros(image_size))
-  variables_axis_resources = jax.tree_map(lambda _: lib.PartitionSpec(),
-                                          variables)
+  variables_axis_resources = jax.tree_util.tree_map(
+      lambda _: lib.PartitionSpec(), variables)
   loss_fn = lambda a, b, _: optax.softmax_cross_entropy(a, b)
   return flax_module, variables, variables_axis_resources, loss_fn, {}, {}
 
diff --git a/vmoe/projects/adversarial_attacks/restore.py b/vmoe/projects/adversarial_attacks/restore.py
index 90ff11e..5bf1245 100644
--- a/vmoe/projects/adversarial_attacks/restore.py
+++ b/vmoe/projects/adversarial_attacks/restore.py
@@ -47,7 +47,7 @@ def compute_loss_predict_cw_fn(x, y, rngs, *, apply_fn, loss_fn):
   # This is a dict mapping from each MoE layer to a binary array of shape
   # (batch_size, num_tokens, num_experts).
   combine_weights = get_combine_weights(intermediates)
-  combine_weights = jax.tree_map(
+  combine_weights = jax.tree_util.tree_map(
       lambda m: m.reshape(batch_size, -1, m.shape[1]), combine_weights)
   return loss, pred, correct, combine_weights
 
diff --git a/vmoe/train/optimizer_test.py b/vmoe/train/optimizer_test.py
index d613481..df9b2da 100644
--- a/vmoe/train/optimizer_test.py
+++ b/vmoe/train/optimizer_test.py
@@ -113,7 +113,7 @@ def step(_, state):
         new_params = optimizer.optax.apply_updates(params, updates)
         return new_params, new_tx_state
 
-      params = jax.tree_map(jnp.asarray, {'x': 0., 'y': 0.})
+      params = jax.tree_util.tree_map(jnp.asarray, {'x': 0., 'y': 0.})
       state = init_fn(params)
       return jax.lax.fori_loop(0, 200, step, (params, state))[0]
 
diff --git a/vmoe/train/trainer.py b/vmoe/train/trainer.py
index b80ffa0..4e07128 100644
--- a/vmoe/train/trainer.py
+++ b/vmoe/train/trainer.py
@@ -415,7 +415,8 @@ def _array_restore_args_fn(x: jax.ShapeDtypeStruct):
           dtype=x.dtype, sharding=x.sharding, global_shape=x.shape)
     restore_kwargs = {
         'state': {
-            'restore_args': jax.tree_map(_array_restore_args_fn, train_state),
+            'restore_args': jax.tree_util.tree_map(
+                _array_restore_args_fn, train_state),
         },
     }
     items = ckpt_manager.restore(
@@ -572,7 +573,7 @@ def mixup(
   Returns:
     A tree with the mixed arrays.
   """
-  arrays, treedef = jax.tree_flatten(tree)
+  arrays, treedef = jax.tree_util.tree_flatten(tree)
   if len(shape) < 2:
     raise ValueError(f"Mixup 'shape' has length {len(shape)}, but it must have "
                      'length >= 2.')
@@ -648,7 +649,7 @@ def compute_grads_and_metrics(params, images, labels, rngs):
     logits, metrics = state.apply_fn({'params': params}, images, rngs=rngs)
     metrics = dict(**metrics)
     metrics['main_loss'] = jnp.mean(loss_fn(logits, labels))
-    metrics = jax.tree_map(jnp.mean, metrics)
+    metrics = jax.tree_util.tree_map(jnp.mean, metrics)
     total_loss = metrics['main_loss'] + metrics.get('auxiliary_loss', 0.0)
     metrics['total_loss'] = total_loss
     return total_loss, (next_rngs, metrics)
diff --git a/vmoe/train/trainer_test.py b/vmoe/train/trainer_test.py
index 0fb575d..6e51871 100644
--- a/vmoe/train/trainer_test.py
+++ b/vmoe/train/trainer_test.py
@@ -732,9 +732,9 @@ def test_granularity(self, granularity):
     np.testing.assert_array_less(np.zeros_like(x),
                                  np.abs(metrics['images'] - x))
     # Convert PRNGKeys to int64 to subtract them.
-    rngs = jax.tree_map(lambda x: np.asarray(x, dtype=np.int64), rngs)
-    new_rngs = jax.tree_map(lambda x: np.asarray(x, dtype=np.int64),
-                            train_state.rngs)
+    rngs = jax.tree_util.tree_map(lambda x: np.asarray(x, dtype=np.int64), rngs)
+    new_rngs = jax.tree_util.tree_map(lambda x: np.asarray(x, dtype=np.int64),
+                                      train_state.rngs)
     # Check that both PRNGKeys have been updated.
     np.testing.assert_array_less(
         np.zeros_like(rngs['mixup']), np.abs(rngs['mixup'] - new_rngs['mixup']))
diff --git a/vmoe/utils.py b/vmoe/utils.py
index ab89971..7f279c8 100644
--- a/vmoe/utils.py
+++ b/vmoe/utils.py
@@ -151,8 +151,9 @@ def safe_zip(*iterables) -> Iterator[Tuple[Any, ...]]:
 
 def tree_rngs_split(rngs, num_splits=2):
   """Splits a PyTree of PRNGKeys into num_splits PyTrees."""
-  rngs = jax.tree_map(lambda rng: jax.random.split(rng, num_splits), rngs)
-  slice_rngs = lambda rngs, i: jax.tree_map(lambda rng: rng[i], rngs)
+  rngs = jax.tree_util.tree_map(
+      lambda rng: jax.random.split(rng, num_splits), rngs)
+  slice_rngs = lambda rngs, i: jax.tree_util.tree_map(lambda rng: rng[i], rngs)
   return tuple(slice_rngs(rngs, i) for i in range(num_splits))