diff --git a/examples/advanced/1_train_act_pusht/act_pusht.yaml b/examples/advanced/1_train_act_pusht/act_pusht.yaml
index 38e542fb..4963e11c 100644
--- a/examples/advanced/1_train_act_pusht/act_pusht.yaml
+++ b/examples/advanced/1_train_act_pusht/act_pusht.yaml
@@ -80,7 +80,7 @@ policy:
   n_vae_encoder_layers: 4
 
   # Inference.
-  temporal_ensemble_momentum: null
+  temporal_ensemble_coeff: null
 
   # Training and loss computation.
   dropout: 0.1
diff --git a/lerobot/common/datasets/lerobot_dataset.py b/lerobot/common/datasets/lerobot_dataset.py
index 1bf336e0..29800c5c 100644
--- a/lerobot/common/datasets/lerobot_dataset.py
+++ b/lerobot/common/datasets/lerobot_dataset.py
@@ -35,15 +35,16 @@ from lerobot.common.datasets.utils import (
 )
 from lerobot.common.datasets.video_utils import VideoFrame, load_from_videos
 
-DATA_DIR = Path(os.environ["DATA_DIR"]) if "DATA_DIR" in os.environ else None
+# For maintainers, see lerobot/common/datasets/push_dataset_to_hub/codebase_version.md
 CODEBASE_VERSION = "v1.5"
 
+DATA_DIR = Path(os.environ["DATA_DIR"]) if "DATA_DIR" in os.environ else None
+
 
 class LeRobotDataset(torch.utils.data.Dataset):
     def __init__(
         self,
         repo_id: str,
-        version: str | None = CODEBASE_VERSION,
         root: Path | None = DATA_DIR,
         split: str = "train",
         image_transforms: Callable | None = None,
@@ -52,7 +53,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
     ):
         super().__init__()
         self.repo_id = repo_id
-        self.version = version
         self.root = root
         self.split = split
         self.image_transforms = image_transforms
@@ -60,16 +60,16 @@ class LeRobotDataset(torch.utils.data.Dataset):
         # load data from hub or locally when root is provided
         # TODO(rcadene, aliberts): implement faster transfer
         # https://huggingface.co/docs/huggingface_hub/en/guides/download#faster-downloads
-        self.hf_dataset = load_hf_dataset(repo_id, version, root, split)
+        self.hf_dataset = load_hf_dataset(repo_id, CODEBASE_VERSION, root, split)
         if split == "train":
-            self.episode_data_index = load_episode_data_index(repo_id, version, root)
+            self.episode_data_index = load_episode_data_index(repo_id, CODEBASE_VERSION, root)
         else:
             self.episode_data_index = calculate_episode_data_index(self.hf_dataset)
             self.hf_dataset = reset_episode_index(self.hf_dataset)
-        self.stats = load_stats(repo_id, version, root)
-        self.info = load_info(repo_id, version, root)
+        self.stats = load_stats(repo_id, CODEBASE_VERSION, root)
+        self.info = load_info(repo_id, CODEBASE_VERSION, root)
         if self.video:
-            self.videos_dir = load_videos(repo_id, version, root)
+            self.videos_dir = load_videos(repo_id, CODEBASE_VERSION, root)
             self.video_backend = video_backend if video_backend is not None else "pyav"
 
     @property
@@ -164,7 +164,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
         return (
             f"{self.__class__.__name__}(\n"
             f"  Repository ID: '{self.repo_id}',\n"
-            f"  Version: '{self.version}',\n"
             f"  Split: '{self.split}',\n"
             f"  Number of Samples: {self.num_samples},\n"
             f"  Number of Episodes: {self.num_episodes},\n"
@@ -173,6 +172,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
             f"  Camera Keys: {self.camera_keys},\n"
             f"  Video Frame Keys: {self.video_frame_keys if self.video else 'N/A'},\n"
             f"  Transformations: {self.image_transforms},\n"
+            f"  Codebase Version: {self.info.get('codebase_version', '< v1.6')},\n"
             f")"
         )
 
@@ -180,7 +180,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
     def from_preloaded(
         cls,
         repo_id: str = "from_preloaded",
-        version: str | None = CODEBASE_VERSION,
         root: Path | None = None,
         split: str = "train",
         transform: callable = None,
@@ -204,7 +203,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
         # create an empty object of type LeRobotDataset
         obj = cls.__new__(cls)
         obj.repo_id = repo_id
-        obj.version = version
         obj.root = root
         obj.split = split
         obj.image_transforms = transform
@@ -228,7 +226,6 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
     def __init__(
         self,
         repo_ids: list[str],
-        version: str | None = CODEBASE_VERSION,
         root: Path | None = DATA_DIR,
         split: str = "train",
         image_transforms: Callable | None = None,
@@ -242,7 +239,6 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
         self._datasets = [
             LeRobotDataset(
                 repo_id,
-                version=version,
                 root=root,
                 split=split,
                 delta_timestamps=delta_timestamps,
@@ -279,7 +275,6 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
             )
             self.disabled_data_keys.update(extra_keys)
 
-        self.version = version
         self.root = root
         self.split = split
         self.image_transforms = image_transforms
@@ -395,7 +390,6 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
         return (
             f"{self.__class__.__name__}(\n"
             f"  Repository IDs: '{self.repo_ids}',\n"
-            f"  Version: '{self.version}',\n"
             f"  Split: '{self.split}',\n"
             f"  Number of Samples: {self.num_samples},\n"
             f"  Number of Episodes: {self.num_episodes},\n"
diff --git a/lerobot/common/datasets/push_dataset_to_hub/CODEBASE_VERSION.md b/lerobot/common/datasets/push_dataset_to_hub/CODEBASE_VERSION.md
new file mode 100644
index 00000000..77948b02
--- /dev/null
+++ b/lerobot/common/datasets/push_dataset_to_hub/CODEBASE_VERSION.md
@@ -0,0 +1,57 @@
+## Using / Updating `CODEBASE_VERSION` (for maintainers)
+
+Since our dataset pushed to the hub are decoupled with the evolution of this repo, we ensure compatibility of
+the datasets with our code, we use a `CODEBASE_VERSION` (defined in
+lerobot/common/datasets/lerobot_dataset.py) variable.
+
+For instance, [`lerobot/pusht`](https://huggingface.co/datasets/lerobot/pusht) has many versions to maintain backward compatibility between LeRobot codebase versions:
+- [v1.0](https://huggingface.co/datasets/lerobot/pusht/tree/v1.0)
+- [v1.1](https://huggingface.co/datasets/lerobot/pusht/tree/v1.1)
+- [v1.2](https://huggingface.co/datasets/lerobot/pusht/tree/v1.2)
+- [v1.3](https://huggingface.co/datasets/lerobot/pusht/tree/v1.3)
+- [v1.4](https://huggingface.co/datasets/lerobot/pusht/tree/v1.4)
+- [v1.5](https://huggingface.co/datasets/lerobot/pusht/tree/v1.5) <-- last version
+- [main](https://huggingface.co/datasets/lerobot/pusht/tree/main) <-- points to the last version
+
+Starting with v1.6, every dataset pushed to the hub or saved locally also have this version number in their
+`info.json` metadata.
+
+### Uploading a new dataset
+If you are pushing a new dataset, you don't need to worry about any of the instructions below, nor to be
+compatible with previous codebase versions. The `push_dataset_to_hub.py` script will automatically tag your
+dataset with the current `CODEBASE_VERSION`.
+
+### Updating an existing dataset
+If you want to update an existing dataset, you need to change the `CODEBASE_VERSION` from `lerobot_dataset.py`
+before running `push_dataset_to_hub.py`. This is especially useful if you introduce a breaking change
+intentionally or not (i.e. something not backward compatible such as modifying the reward functions used,
+deleting some frames at the end of an episode, etc.). That way, people running a previous version of the
+codebase won't be affected by your change and backward compatibility is maintained.
+
+However, you will need to update the version of ALL the other datasets so that they have the new
+`CODEBASE_VERSION` as a branch in their hugging face dataset repository. Don't worry, there is an easy way
+that doesn't require to run `push_dataset_to_hub.py`. You can just "branch-out" from the `main` branch on HF
+dataset repo by running this script which corresponds to a `git checkout -b` (so no copy or upload needed):
+
+```python
+from huggingface_hub import HfApi
+
+from lerobot import available_datasets
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
+
+api = HfApi()
+
+for repo_id in available_datasets:
+    dataset_info = api.list_repo_refs(repo_id, repo_type="dataset")
+    branches = [b.name for b in dataset_info.branches]
+    if CODEBASE_VERSION in branches:
+        # First check if the newer version already exists.
+        print(f"Found existing branch for {repo_id}. Please contact a member of the core LeRobot team.")
+        print("Exiting early")
+        break
+    else:
+        # Now create a branch named after the new version by branching out from "main"
+        # which is expected to be the preceding version
+        api.create_branch(repo_id, repo_type="dataset", branch=CODEBASE_VERSION, revision="main")
+        print(f"{repo_id} successfully updated")
+```
diff --git a/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py b/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py
index 91ba9ef1..b630bbca 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py
@@ -32,46 +32,41 @@ from pathlib import Path
 from huggingface_hub import snapshot_download
 
 AVAILABLE_RAW_REPO_IDS = [
-    "cadene/pusht_image_raw",
-    "cadene/xarm_lift_medium_image_raw",
-    "cadene/xarm_lift_medium_replay_image_raw",
-    "cadene/xarm_push_medium_image_raw",
-    "cadene/xarm_push_medium_replay_image_raw",
-    "cadene/aloha_sim_insertion_human_image_raw",
-    "cadene/aloha_sim_insertion_scripted_image_raw",
-    "cadene/aloha_sim_transfer_cube_human_image_raw",
-    "cadene/aloha_sim_transfer_cube_scripted_image_raw",
-    "cadene/pusht_raw",
-    "cadene/xarm_lift_medium_raw",
-    "cadene/xarm_lift_medium_replay_raw",
-    "cadene/xarm_push_medium_raw",
-    "cadene/xarm_push_medium_replay_raw",
-    "cadene/aloha_sim_insertion_human_raw",
-    "cadene/aloha_sim_insertion_scripted_raw",
-    "cadene/aloha_sim_transfer_cube_human_raw",
-    "cadene/aloha_sim_transfer_cube_scripted_raw",
-    "cadene/aloha_mobile_cabinet_raw",
-    "cadene/aloha_mobile_chair_raw",
-    "cadene/aloha_mobile_elevator_raw",
-    "cadene/aloha_mobile_shrimp_raw",
-    "cadene/aloha_mobile_wash_pan_raw",
-    "cadene/aloha_mobile_wipe_wine_raw",
-    "cadene/aloha_static_battery_raw",
-    "cadene/aloha_static_candy_raw",
-    "cadene/aloha_static_coffee_raw",
-    "cadene/aloha_static_coffee_new_raw",
-    "cadene/aloha_static_cups_open_raw",
-    "cadene/aloha_static_fork_pick_up_raw",
-    "cadene/aloha_static_pingpong_test_raw",
-    "cadene/aloha_static_pro_pencil_raw",
-    "cadene/aloha_static_screw_driver_raw",
-    "cadene/aloha_static_tape_raw",
-    "cadene/aloha_static_thread_velcro_raw",
-    "cadene/aloha_static_towel_raw",
-    "cadene/aloha_static_vinh_cup_raw",
-    "cadene/aloha_static_vinh_cup_left_raw",
-    "cadene/aloha_static_ziploc_slide_raw",
-    "cadene/umi_cup_in_the_wild_raw",
+    "lerobot-raw/aloha_mobile_cabinet_raw",
+    "lerobot-raw/aloha_mobile_chair_raw",
+    "lerobot-raw/aloha_mobile_elevator_raw",
+    "lerobot-raw/aloha_mobile_shrimp_raw",
+    "lerobot-raw/aloha_mobile_wash_pan_raw",
+    "lerobot-raw/aloha_mobile_wipe_wine_raw",
+    "lerobot-raw/aloha_sim_insertion_human_raw",
+    "lerobot-raw/aloha_sim_insertion_scripted_raw",
+    "lerobot-raw/aloha_sim_transfer_cube_human_raw",
+    "lerobot-raw/aloha_sim_transfer_cube_scripted_raw",
+    "lerobot-raw/aloha_static_battery_raw",
+    "lerobot-raw/aloha_static_candy_raw",
+    "lerobot-raw/aloha_static_coffee_new_raw",
+    "lerobot-raw/aloha_static_coffee_raw",
+    "lerobot-raw/aloha_static_cups_open_raw",
+    "lerobot-raw/aloha_static_fork_pick_up_raw",
+    "lerobot-raw/aloha_static_pingpong_test_raw",
+    "lerobot-raw/aloha_static_pro_pencil_raw",
+    "lerobot-raw/aloha_static_screw_driver_raw",
+    "lerobot-raw/aloha_static_tape_raw",
+    "lerobot-raw/aloha_static_thread_velcro_raw",
+    "lerobot-raw/aloha_static_towel_raw",
+    "lerobot-raw/aloha_static_vinh_cup_left_raw",
+    "lerobot-raw/aloha_static_vinh_cup_raw",
+    "lerobot-raw/aloha_static_ziploc_slide_raw",
+    "lerobot-raw/pusht_raw",
+    "lerobot-raw/umi_cup_in_the_wild_raw",
+    "lerobot-raw/unitreeh1_fold_clothes_raw",
+    "lerobot-raw/unitreeh1_rearrange_objects_raw",
+    "lerobot-raw/unitreeh1_two_robot_greeting_raw",
+    "lerobot-raw/unitreeh1_warehouse_raw",
+    "lerobot-raw/xarm_lift_medium_raw",
+    "lerobot-raw/xarm_lift_medium_replay_raw",
+    "lerobot-raw/xarm_push_medium_raw",
+    "lerobot-raw/xarm_push_medium_replay_raw",
 ]
 
 
@@ -89,7 +84,6 @@ def download_raw(raw_dir: Path, repo_id: str):
             stacklevel=1,
         )
 
-    raw_dir = Path(raw_dir)
     # Send warning if raw_dir isn't well formated
     if raw_dir.parts[-2] != user_id or raw_dir.parts[-1] != dataset_id:
         warnings.warn(
@@ -99,7 +93,7 @@ def download_raw(raw_dir: Path, repo_id: str):
     raw_dir.mkdir(parents=True, exist_ok=True)
 
     logging.info(f"Start downloading from huggingface.co/{user_id} for {dataset_id}")
-    snapshot_download(f"{repo_id}", repo_type="dataset", local_dir=raw_dir)
+    snapshot_download(repo_id, repo_type="dataset", local_dir=raw_dir)
     logging.info(f"Finish downloading from huggingface.co/{user_id} for {dataset_id}")
 
 
diff --git a/lerobot/common/datasets/push_dataset_to_hub/aloha_hdf5_format.py b/lerobot/common/datasets/push_dataset_to_hub/aloha_hdf5_format.py
index 024045a0..24873ca2 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/aloha_hdf5_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/aloha_hdf5_format.py
@@ -28,6 +28,7 @@ import tqdm
 from datasets import Dataset, Features, Image, Sequence, Value
 from PIL import Image as PILImage
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.push_dataset_to_hub.utils import concatenate_episodes, save_images_concurrently
 from lerobot.common.datasets.utils import (
     calculate_episode_data_index,
@@ -210,6 +211,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/common/datasets/push_dataset_to_hub/cam_png_format.py b/lerobot/common/datasets/push_dataset_to_hub/cam_png_format.py
index 4972e6b4..52eabd99 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/cam_png_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/cam_png_format.py
@@ -23,6 +23,7 @@ import torch
 from datasets import Dataset, Features, Image, Value
 from PIL import Image as PILImage
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.push_dataset_to_hub.utils import concatenate_episodes
 from lerobot.common.datasets.utils import calculate_episode_data_index, hf_transform_to_torch
 from lerobot.common.datasets.video_utils import VideoFrame
@@ -95,6 +96,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/common/datasets/push_dataset_to_hub/dora_parquet_format.py b/lerobot/common/datasets/push_dataset_to_hub/dora_parquet_format.py
index 1dc2e67e..832f3af2 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/dora_parquet_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/dora_parquet_format.py
@@ -24,6 +24,7 @@ import pandas as pd
 import torch
 from datasets import Dataset, Features, Image, Sequence, Value
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.utils import (
     calculate_episode_data_index,
     hf_transform_to_torch,
@@ -214,6 +215,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_df, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/common/datasets/push_dataset_to_hub/pusht_zarr_format.py b/lerobot/common/datasets/push_dataset_to_hub/pusht_zarr_format.py
index 69b23a47..54043eee 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/pusht_zarr_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/pusht_zarr_format.py
@@ -25,6 +25,7 @@ import zarr
 from datasets import Dataset, Features, Image, Sequence, Value
 from PIL import Image as PILImage
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.push_dataset_to_hub.utils import concatenate_episodes, save_images_concurrently
 from lerobot.common.datasets.utils import (
     calculate_episode_data_index,
@@ -258,6 +259,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_dict, video, keypoints_instead_of_image)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video if not keypoints_instead_of_image else 0,
     }
diff --git a/lerobot/common/datasets/push_dataset_to_hub/umi_zarr_format.py b/lerobot/common/datasets/push_dataset_to_hub/umi_zarr_format.py
index 6cd80c61..f9ac849c 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/umi_zarr_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/umi_zarr_format.py
@@ -25,6 +25,7 @@ import zarr
 from datasets import Dataset, Features, Image, Sequence, Value
 from PIL import Image as PILImage
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.push_dataset_to_hub._umi_imagecodecs_numcodecs import register_codecs
 from lerobot.common.datasets.push_dataset_to_hub.utils import concatenate_episodes, save_images_concurrently
 from lerobot.common.datasets.utils import (
@@ -199,6 +200,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/common/datasets/push_dataset_to_hub/xarm_pkl_format.py b/lerobot/common/datasets/push_dataset_to_hub/xarm_pkl_format.py
index 57a36dba..d6ffbea1 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/xarm_pkl_format.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/xarm_pkl_format.py
@@ -25,6 +25,7 @@ import tqdm
 from datasets import Dataset, Features, Image, Sequence, Value
 from PIL import Image as PILImage
 
+from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
 from lerobot.common.datasets.push_dataset_to_hub.utils import concatenate_episodes, save_images_concurrently
 from lerobot.common.datasets.utils import (
     calculate_episode_data_index,
@@ -177,6 +178,7 @@ def from_raw_to_lerobot_format(
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/common/datasets/utils.py b/lerobot/common/datasets/utils.py
index cb2fee95..af1a3db6 100644
--- a/lerobot/common/datasets/utils.py
+++ b/lerobot/common/datasets/utils.py
@@ -15,13 +15,15 @@
 # limitations under the License.
 import json
 import re
+import warnings
+from functools import cache
 from pathlib import Path
 from typing import Dict
 
 import datasets
 import torch
 from datasets import load_dataset, load_from_disk
-from huggingface_hub import hf_hub_download, snapshot_download
+from huggingface_hub import HfApi, hf_hub_download, snapshot_download
 from PIL import Image as PILImage
 from safetensors.torch import load_file
 from torchvision import transforms
@@ -80,7 +82,28 @@ def hf_transform_to_torch(items_dict: dict[torch.Tensor | None]):
     return items_dict
 
 
-def load_hf_dataset(repo_id, version, root, split) -> datasets.Dataset:
+@cache
+def get_hf_dataset_safe_version(repo_id: str, version: str) -> str:
+    api = HfApi()
+    dataset_info = api.list_repo_refs(repo_id, repo_type="dataset")
+    branches = [b.name for b in dataset_info.branches]
+    if version not in branches:
+        warnings.warn(
+            f"""You are trying to load a dataset from {repo_id} created with a previous version of the
+            codebase. The following versions are available: {branches}.
+            The requested version ('{version}') is not found. You should be fine since
+            backward compatibility is maintained. If you encounter a problem, contact LeRobot maintainers on
+            Discord ('https://discord.com/invite/s3KuuzsPFb') or open an issue on github.""",
+            stacklevel=1,
+        )
+        if "main" not in branches:
+            raise ValueError(f"Version 'main' not found on {repo_id}")
+        return "main"
+    else:
+        return version
+
+
+def load_hf_dataset(repo_id: str, version: str, root: Path, split: str) -> datasets.Dataset:
     """hf_dataset contains all the observations, states, actions, rewards, etc."""
     if root is not None:
         hf_dataset = load_from_disk(str(Path(root) / repo_id / "train"))
@@ -101,7 +124,9 @@ def load_hf_dataset(repo_id, version, root, split) -> datasets.Dataset:
                     f'`split` ({split}) should either be "train", "train[INT:]", or "train[:INT]"'
                 )
     else:
-        hf_dataset = load_dataset(repo_id, revision=version, split=split)
+        safe_version = get_hf_dataset_safe_version(repo_id, version)
+        hf_dataset = load_dataset(repo_id, revision=safe_version, split=split)
+
     hf_dataset.set_transform(hf_transform_to_torch)
     return hf_dataset
 
@@ -119,8 +144,9 @@ def load_episode_data_index(repo_id, version, root) -> dict[str, torch.Tensor]:
     if root is not None:
         path = Path(root) / repo_id / "meta_data" / "episode_data_index.safetensors"
     else:
+        safe_version = get_hf_dataset_safe_version(repo_id, version)
         path = hf_hub_download(
-            repo_id, "meta_data/episode_data_index.safetensors", repo_type="dataset", revision=version
+            repo_id, "meta_data/episode_data_index.safetensors", repo_type="dataset", revision=safe_version
         )
 
     return load_file(path)
@@ -137,7 +163,10 @@ def load_stats(repo_id, version, root) -> dict[str, dict[str, torch.Tensor]]:
     if root is not None:
         path = Path(root) / repo_id / "meta_data" / "stats.safetensors"
     else:
-        path = hf_hub_download(repo_id, "meta_data/stats.safetensors", repo_type="dataset", revision=version)
+        safe_version = get_hf_dataset_safe_version(repo_id, version)
+        path = hf_hub_download(
+            repo_id, "meta_data/stats.safetensors", repo_type="dataset", revision=safe_version
+        )
 
     stats = load_file(path)
     return unflatten_dict(stats)
@@ -154,7 +183,8 @@ def load_info(repo_id, version, root) -> dict:
     if root is not None:
         path = Path(root) / repo_id / "meta_data" / "info.json"
     else:
-        path = hf_hub_download(repo_id, "meta_data/info.json", repo_type="dataset", revision=version)
+        safe_version = get_hf_dataset_safe_version(repo_id, version)
+        path = hf_hub_download(repo_id, "meta_data/info.json", repo_type="dataset", revision=safe_version)
 
     with open(path) as f:
         info = json.load(f)
@@ -166,7 +196,8 @@ def load_videos(repo_id, version, root) -> Path:
         path = Path(root) / repo_id / "videos"
     else:
         # TODO(rcadene): we download the whole repo here. see if we can avoid this
-        repo_dir = snapshot_download(repo_id, repo_type="dataset", revision=version)
+        safe_version = get_hf_dataset_safe_version(repo_id, version)
+        repo_dir = snapshot_download(repo_id, repo_type="dataset", revision=safe_version)
         path = Path(repo_dir) / "videos"
 
     return path
diff --git a/lerobot/common/policies/act/configuration_act.py b/lerobot/common/policies/act/configuration_act.py
index 92a52eac..a86c359c 100644
--- a/lerobot/common/policies/act/configuration_act.py
+++ b/lerobot/common/policies/act/configuration_act.py
@@ -76,12 +76,10 @@ class ACTConfig:
             documentation in the policy class).
         latent_dim: The VAE's latent dimension.
         n_vae_encoder_layers: The number of transformer layers to use for the VAE's encoder.
-        temporal_ensemble_momentum: Exponential moving average (EMA) momentum parameter (α) for ensembling
-            actions for a given time step over multiple policy invocations. Updates are calculated as:
-            x⁻ₙ = αx⁻ₙ₋₁ + (1-α)xₙ. Note that the ACT paper and original ACT code describes a different
-            parameter here: they refer to a weighting scheme wᵢ = exp(-m⋅i) and set m = 0.01. With our
-            formulation, this is equivalent to α = exp(-0.01) ≈ 0.99. When this parameter is provided, we
-            require `n_action_steps == 1` (since we need to query the policy every step anyway).
+        temporal_ensemble_coeff: Coefficient for the exponential weighting scheme to apply for temporal
+            ensembling. Defaults to None which means temporal ensembling is not used. `n_action_steps` must be
+            1 when using this feature, as inference needs to happen at every step to form an ensemble. For
+            more information on how ensembling works, please see `ACTTemporalEnsembler`.
         dropout: Dropout to use in the transformer layers (see code for details).
         kl_weight: The weight to use for the KL-divergence component of the loss if the variational objective
             is enabled. Loss is then calculated as: `reconstruction_loss + kl_weight * kld_loss`.
@@ -139,7 +137,8 @@ class ACTConfig:
     n_vae_encoder_layers: int = 4
 
     # Inference.
-    temporal_ensemble_momentum: float | None = None
+    # Note: the value used in ACT when temporal ensembling is enabled is 0.01.
+    temporal_ensemble_coeff: float | None = None
 
     # Training and loss computation.
     dropout: float = 0.1
@@ -151,7 +150,7 @@ class ACTConfig:
             raise ValueError(
                 f"`vision_backbone` must be one of the ResNet variants. Got {self.vision_backbone}."
             )
-        if self.temporal_ensemble_momentum is not None and self.n_action_steps > 1:
+        if self.temporal_ensemble_coeff is not None and self.n_action_steps > 1:
             raise NotImplementedError(
                 "`n_action_steps` must be 1 when using temporal ensembling. This is "
                 "because the policy needs to be queried every step to compute the ensembled action."
diff --git a/lerobot/common/policies/act/modeling_act.py b/lerobot/common/policies/act/modeling_act.py
index 0a236100..c072c31e 100644
--- a/lerobot/common/policies/act/modeling_act.py
+++ b/lerobot/common/policies/act/modeling_act.py
@@ -77,12 +77,15 @@ class ACTPolicy(nn.Module, PyTorchModelHubMixin):
 
         self.expected_image_keys = [k for k in config.input_shapes if k.startswith("observation.image")]
 
+        if config.temporal_ensemble_coeff is not None:
+            self.temporal_ensembler = ACTTemporalEnsembler(config.temporal_ensemble_coeff, config.chunk_size)
+
         self.reset()
 
     def reset(self):
         """This should be called whenever the environment is reset."""
-        if self.config.temporal_ensemble_momentum is not None:
-            self._ensembled_actions = None
+        if self.config.temporal_ensemble_coeff is not None:
+            self.temporal_ensembler.reset()
         else:
             self._action_queue = deque([], maxlen=self.config.n_action_steps)
 
@@ -100,24 +103,12 @@ class ACTPolicy(nn.Module, PyTorchModelHubMixin):
         if len(self.expected_image_keys) > 0:
             batch["observation.images"] = torch.stack([batch[k] for k in self.expected_image_keys], dim=-4)
 
-        # If we are doing temporal ensembling, keep track of the exponential moving average (EMA), and return
-        # the first action.
-        if self.config.temporal_ensemble_momentum is not None:
+        # If we are doing temporal ensembling, do online updates where we keep track of the number of actions
+        # we are ensembling over.
+        if self.config.temporal_ensemble_coeff is not None:
             actions = self.model(batch)[0]  # (batch_size, chunk_size, action_dim)
             actions = self.unnormalize_outputs({"action": actions})["action"]
-            if self._ensembled_actions is None:
-                # Initializes `self._ensembled_action` to the sequence of actions predicted during the first
-                # time step of the episode.
-                self._ensembled_actions = actions.clone()
-            else:
-                # self._ensembled_actions will have shape (batch_size, chunk_size - 1, action_dim). Compute
-                # the EMA update for those entries.
-                alpha = self.config.temporal_ensemble_momentum
-                self._ensembled_actions = alpha * self._ensembled_actions + (1 - alpha) * actions[:, :-1]
-                # The last action, which has no prior moving average, needs to get concatenated onto the end.
-                self._ensembled_actions = torch.cat([self._ensembled_actions, actions[:, -1:]], dim=1)
-            # "Consume" the first action.
-            action, self._ensembled_actions = self._ensembled_actions[:, 0], self._ensembled_actions[:, 1:]
+            action = self.temporal_ensembler.update(actions)
             return action
 
         # Action queue logic for n_action_steps > 1. When the action_queue is depleted, populate it by
@@ -162,6 +153,97 @@ class ACTPolicy(nn.Module, PyTorchModelHubMixin):
         return loss_dict
 
 
+class ACTTemporalEnsembler:
+    def __init__(self, temporal_ensemble_coeff: float, chunk_size: int) -> None:
+        """Temporal ensembling as described in Algorithm 2 of https://arxiv.org/abs/2304.13705.
+
+        The weights are calculated as wᵢ = exp(-temporal_ensemble_coeff * i) where w₀ is the oldest action.
+        They are then normalized to sum to 1 by dividing by Σwᵢ. Here's some intuition around how the
+        coefficient works:
+            - Setting it to 0 uniformly weighs all actions.
+            - Setting it positive gives more weight to older actions.
+            - Setting it negative gives more weight to newer actions.
+        NOTE: The default value for `temporal_ensemble_coeff` used by the original ACT work is 0.01. This
+        results in older actions being weighed more highly than newer actions (the experiments documented in
+        https://github.com/huggingface/lerobot/pull/319 hint at why highly weighing new actions might be
+        detrimental: doing so aggressively may diminish the benefits of action chunking).
+
+        Here we use an online method for computing the average rather than caching a history of actions in
+        order to compute the average offline. For a simple 1D sequence it looks something like:
+
+        ```
+        import torch
+
+        seq = torch.linspace(8, 8.5, 100)
+        print(seq)
+
+        m = 0.01
+        exp_weights = torch.exp(-m * torch.arange(len(seq)))
+        print(exp_weights)
+
+        # Calculate offline
+        avg = (exp_weights * seq).sum() / exp_weights.sum()
+        print("offline", avg)
+
+        # Calculate online
+        for i, item in enumerate(seq):
+            if i == 0:
+                avg = item
+                continue
+            avg *= exp_weights[:i].sum()
+            avg += item * exp_weights[i]
+            avg /= exp_weights[:i+1].sum()
+        print("online", avg)
+        ```
+        """
+        self.chunk_size = chunk_size
+        self.ensemble_weights = torch.exp(-temporal_ensemble_coeff * torch.arange(chunk_size))
+        self.ensemble_weights_cumsum = torch.cumsum(self.ensemble_weights, dim=0)
+        self.reset()
+
+    def reset(self):
+        """Resets the online computation variables."""
+        self.ensembled_actions = None
+        # (chunk_size,) count of how many actions are in the ensemble for each time step in the sequence.
+        self.ensembled_actions_count = None
+
+    def update(self, actions: Tensor) -> Tensor:
+        """
+        Takes a (batch, chunk_size, action_dim) sequence of actions, update the temporal ensemble for all
+        time steps, and pop/return the next batch of actions in the sequence.
+        """
+        self.ensemble_weights = self.ensemble_weights.to(device=actions.device)
+        self.ensemble_weights_cumsum = self.ensemble_weights_cumsum.to(device=actions.device)
+        if self.ensembled_actions is None:
+            # Initializes `self._ensembled_action` to the sequence of actions predicted during the first
+            # time step of the episode.
+            self.ensembled_actions = actions.clone()
+            # Note: The last dimension is unsqueeze to make sure we can broadcast properly for tensor
+            # operations later.
+            self.ensembled_actions_count = torch.ones(
+                (self.chunk_size, 1), dtype=torch.long, device=self.ensembled_actions.device
+            )
+        else:
+            # self.ensembled_actions will have shape (batch_size, chunk_size - 1, action_dim). Compute
+            # the online update for those entries.
+            self.ensembled_actions *= self.ensemble_weights_cumsum[self.ensembled_actions_count - 1]
+            self.ensembled_actions += actions[:, :-1] * self.ensemble_weights[self.ensembled_actions_count]
+            self.ensembled_actions /= self.ensemble_weights_cumsum[self.ensembled_actions_count]
+            self.ensembled_actions_count = torch.clamp(self.ensembled_actions_count + 1, max=self.chunk_size)
+            # The last action, which has no prior online average, needs to get concatenated onto the end.
+            self.ensembled_actions = torch.cat([self.ensembled_actions, actions[:, -1:]], dim=1)
+            self.ensembled_actions_count = torch.cat(
+                [self.ensembled_actions_count, torch.ones_like(self.ensembled_actions_count[-1:])]
+            )
+        # "Consume" the first action.
+        action, self.ensembled_actions, self.ensembled_actions_count = (
+            self.ensembled_actions[:, 0],
+            self.ensembled_actions[:, 1:],
+            self.ensembled_actions_count[1:],
+        )
+        return action
+
+
 class ACT(nn.Module):
     """Action Chunking Transformer: The underlying neural network for ACTPolicy.
 
diff --git a/lerobot/configs/policy/act.yaml b/lerobot/configs/policy/act.yaml
index ea2c5b75..28883936 100644
--- a/lerobot/configs/policy/act.yaml
+++ b/lerobot/configs/policy/act.yaml
@@ -75,7 +75,7 @@ policy:
   n_vae_encoder_layers: 4
 
   # Inference.
-  temporal_ensemble_momentum: null
+  temporal_ensemble_coeff: null
 
   # Training and loss computation.
   dropout: 0.1
diff --git a/lerobot/configs/policy/act_real.yaml b/lerobot/configs/policy/act_real.yaml
index c2f7158f..058104f4 100644
--- a/lerobot/configs/policy/act_real.yaml
+++ b/lerobot/configs/policy/act_real.yaml
@@ -107,7 +107,7 @@ policy:
   n_vae_encoder_layers: 4
 
   # Inference.
-  temporal_ensemble_momentum: null
+  temporal_ensemble_coeff: null
 
   # Training and loss computation.
   dropout: 0.1
diff --git a/lerobot/configs/policy/act_real_no_state.yaml b/lerobot/configs/policy/act_real_no_state.yaml
index 5b8a13b4..08261050 100644
--- a/lerobot/configs/policy/act_real_no_state.yaml
+++ b/lerobot/configs/policy/act_real_no_state.yaml
@@ -103,7 +103,7 @@ policy:
   n_vae_encoder_layers: 4
 
   # Inference.
-  temporal_ensemble_momentum: null
+  temporal_ensemble_coeff: null
 
   # Training and loss computation.
   dropout: 0.1
diff --git a/lerobot/scripts/control_robot.py b/lerobot/scripts/control_robot.py
index d7d3b25e..e7c83880 100644
--- a/lerobot/scripts/control_robot.py
+++ b/lerobot/scripts/control_robot.py
@@ -494,6 +494,7 @@ def record_dataset(
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
     info = {
+        "codebase_version": CODEBASE_VERSION,
         "fps": fps,
         "video": video,
     }
diff --git a/lerobot/scripts/push_dataset_to_hub.py b/lerobot/scripts/push_dataset_to_hub.py
index fe62e7c1..ce1a06f7 100644
--- a/lerobot/scripts/push_dataset_to_hub.py
+++ b/lerobot/scripts/push_dataset_to_hub.py
@@ -40,60 +40,6 @@ python lerobot/scripts/push_dataset_to_hub.py \
 --raw-format umi_zarr \
 --repo-id lerobot/umi_cup_in_the_wild
 ```
-
-**WARNING: Updating an existing dataset**
-
-If you want to update an existing dataset, you need to change the `CODEBASE_VERSION` from `lerobot_dataset.py`
-before running `push_dataset_to_hub.py`. This is especially useful if you introduce a breaking change
-intentionally or not (i.e. something not backward compatible such as modifying the reward functions used,
-deleting some frames at the end of an episode, etc.). That way, people running a previous version of the
-codebase won't be affected by your change and backward compatibility is maintained.
-
-For instance, Pusht has many versions to maintain backward compatibility between LeRobot codebase versions:
-- [v1.0](https://huggingface.co/datasets/lerobot/pusht/tree/v1.0)
-- [v1.1](https://huggingface.co/datasets/lerobot/pusht/tree/v1.1)
-- [v1.2](https://huggingface.co/datasets/lerobot/pusht/tree/v1.2)
-- [v1.3](https://huggingface.co/datasets/lerobot/pusht/tree/v1.3)
-- [v1.4](https://huggingface.co/datasets/lerobot/pusht/tree/v1.4)
-- [v1.5](https://huggingface.co/datasets/lerobot/pusht/tree/v1.5) <-- last version
-- [main](https://huggingface.co/datasets/lerobot/pusht/tree/main)  <-- points to the last version
-
-However, you will need to update the version of ALL the other datasets so that they have the new
-`CODEBASE_VERSION` as a branch in their hugging face dataset repository. Don't worry, there is an easy way
-that doesn't require to run `push_dataset_to_hub.py`. You can just "branch-out" from the `main` branch on HF
-dataset repo by running this script which corresponds to a `git checkout -b` (so no copy or upload needed):
-
-```python
-import os
-
-from huggingface_hub import create_branch, hf_hub_download
-from huggingface_hub.utils._errors import RepositoryNotFoundError
-
-from lerobot import available_datasets
-from lerobot.common.datasets.lerobot_dataset import CODEBASE_VERSION
-
-os.environ["HF_HUB_DISABLE_PROGRESS_BARS"] = "1"  # makes it easier to see the print-out below
-
-NEW_CODEBASE_VERSION = "v1.5"  # REPLACE THIS WITH YOUR DESIRED VERSION
-
-for repo_id in available_datasets:
-    # First check if the newer version already exists.
-    try:
-        hf_hub_download(
-            repo_id=repo_id, repo_type="dataset", filename=".gitattributes", revision=NEW_CODEBASE_VERSION
-        )
-        print(f"Found existing branch for {repo_id}. Please contact a member of the core LeRobot team.")
-        print("Exiting early")
-        break
-    except RepositoryNotFoundError:
-        # Now create a branch.
-        create_branch(repo_id, repo_type="dataset", branch=NEW_CODEBASE_VERSION, revision=CODEBASE_VERSION)
-        print(f"{repo_id} successfully updated")
-
-```
-
-On the other hand, if you are pushing a new dataset, you don't need to worry about any of the instructions
-above, nor to be compatible with previous codebase versions.
 """
 
 import argparse
@@ -104,7 +50,7 @@ from pathlib import Path
 from typing import Any
 
 import torch
-from huggingface_hub import HfApi, create_branch
+from huggingface_hub import HfApi
 from safetensors.torch import save_file
 
 from lerobot.common.datasets.compute_stats import compute_stats
@@ -270,7 +216,8 @@ def push_dataset_to_hub(
         push_meta_data_to_hub(repo_id, meta_data_dir, revision="main")
         if video:
             push_videos_to_hub(repo_id, videos_dir, revision="main")
-        create_branch(repo_id, repo_type="dataset", branch=CODEBASE_VERSION)
+        api = HfApi()
+        api.create_branch(repo_id, repo_type="dataset", branch=CODEBASE_VERSION)
 
     if tests_data_dir:
         # get the first episode
diff --git a/lerobot/scripts/train.py b/lerobot/scripts/train.py
index 4e636db8..f707fe12 100644
--- a/lerobot/scripts/train.py
+++ b/lerobot/scripts/train.py
@@ -272,7 +272,8 @@ def train(cfg: DictConfig, out_dir: str | None = None, job_name: str | None = No
         cfg.resume = True
     elif Logger.get_last_checkpoint_dir(out_dir).exists():
         raise RuntimeError(
-            f"The configured output directory {Logger.get_last_checkpoint_dir(out_dir)} already exists."
+            f"The configured output directory {Logger.get_last_checkpoint_dir(out_dir)} already exists. If "
+            "you meant to resume training, please use `resume=true` in your command or yaml configuration."
         )
 
     # log metrics to terminal and wandb
diff --git a/tests/test_policies.py b/tests/test_policies.py
index bc9c34ff..63f394e9 100644
--- a/tests/test_policies.py
+++ b/tests/test_policies.py
@@ -16,6 +16,7 @@
 import inspect
 from pathlib import Path
 
+import einops
 import pytest
 import torch
 from huggingface_hub import PyTorchModelHubMixin
@@ -26,6 +27,7 @@ from lerobot.common.datasets.factory import make_dataset
 from lerobot.common.datasets.utils import cycle
 from lerobot.common.envs.factory import make_env
 from lerobot.common.envs.utils import preprocess_observation
+from lerobot.common.policies.act.modeling_act import ACTTemporalEnsembler
 from lerobot.common.policies.factory import (
     _policy_cfg_from_hydra_cfg,
     get_policy_and_config_classes,
@@ -33,7 +35,7 @@ from lerobot.common.policies.factory import (
 )
 from lerobot.common.policies.normalize import Normalize, Unnormalize
 from lerobot.common.policies.policy_protocol import Policy
-from lerobot.common.utils.utils import init_hydra_config
+from lerobot.common.utils.utils import init_hydra_config, seeded_context
 from lerobot.scripts.train import make_optimizer_and_scheduler
 from tests.scripts.save_policy_to_safetensors import get_policy_stats
 from tests.utils import DEFAULT_CONFIG_PATH, DEVICE, require_cpu, require_env, require_x86_64_kernel
@@ -390,3 +392,62 @@ def test_backward_compatibility(env_name, policy_name, extra_overrides, file_nam
         assert torch.isclose(param_stats[key], saved_param_stats[key], rtol=50, atol=1e-7).all()
     for key in saved_actions:
         assert torch.isclose(actions[key], saved_actions[key], rtol=0.1, atol=1e-7).all()
+
+
+def test_act_temporal_ensembler():
+    """Check that the online method in ACTTemporalEnsembler matches a simple offline calculation."""
+    temporal_ensemble_coeff = 0.01
+    chunk_size = 100
+    episode_length = 101
+    ensembler = ACTTemporalEnsembler(temporal_ensemble_coeff, chunk_size)
+    # An batch of arbitrary sequences of 1D actions we wish to compute the average over. We'll keep the
+    # "action space" in [-1, 1]. Apart from that, there is no real reason for the numbers chosen.
+    with seeded_context(0):
+        # Dimension is (batch, episode_length, chunk_size, action_dim(=1))
+        # Stepping through the episode_length dim is like running inference at each rollout step and getting
+        # a different action chunk.
+        batch_seq = torch.stack(
+            [
+                torch.rand(episode_length, chunk_size) * 0.05 - 0.6,
+                torch.rand(episode_length, chunk_size) * 0.02 - 0.01,
+                torch.rand(episode_length, chunk_size) * 0.2 + 0.3,
+            ],
+            dim=0,
+        ).unsqueeze(-1)  # unsqueeze for action dim
+    batch_size = batch_seq.shape[0]
+    # Exponential weighting (normalized). Unsqueeze once to match the position of the `episode_length`
+    # dimension of `batch_seq`.
+    weights = torch.exp(-temporal_ensemble_coeff * torch.arange(chunk_size)).unsqueeze(-1)
+
+    # Simulate stepping through a rollout and computing a batch of actions with model on each step.
+    for i in range(episode_length):
+        # Mock a batch of actions.
+        actions = torch.zeros(size=(batch_size, chunk_size, 1)) + batch_seq[:, i]
+        online_avg = ensembler.update(actions)
+        # Simple offline calculation: avg = Σ(aᵢ*wᵢ) / Σ(wᵢ).
+        # Note: The complicated bit here is the slicing. Think about the (episode_length, chunk_size) grid.
+        # What we want to do is take diagonal slices across it starting from the left.
+        #  eg: chunk_size=4, episode_length=6
+        #  ┌───────┐
+        #  │0 1 2 3│
+        #  │1 2 3 4│
+        #  │2 3 4 5│
+        #  │3 4 5 6│
+        #  │4 5 6 7│
+        #  │5 6 7 8│
+        #  └───────┘
+        chunk_indices = torch.arange(min(i, chunk_size - 1), -1, -1)
+        episode_step_indices = torch.arange(i + 1)[-len(chunk_indices) :]
+        seq_slice = batch_seq[:, episode_step_indices, chunk_indices]
+        offline_avg = (
+            einops.reduce(seq_slice * weights[: i + 1], "b s 1 -> b 1", "sum") / weights[: i + 1].sum()
+        )
+        # Sanity check. The average should be between the extrema.
+        assert torch.all(einops.reduce(seq_slice, "b s 1 -> b 1", "min") <= offline_avg)
+        assert torch.all(offline_avg <= einops.reduce(seq_slice, "b s 1 -> b 1", "max"))
+        # Selected atol=1e-4 keeping in mind actions in [-1, 1] and excepting 0.01% error.
+        assert torch.allclose(online_avg, offline_avg, atol=1e-4)
+
+
+if __name__ == "__main__":
+    test_act_temporal_ensembler()