diff --git a/lerobot/common/datasets/compute_stats.py b/lerobot/common/datasets/compute_stats.py
index 1149ec83e..7d8dd7c2b 100644
--- a/lerobot/common/datasets/compute_stats.py
+++ b/lerobot/common/datasets/compute_stats.py
@@ -108,7 +108,7 @@ def compute_episode_stats(episode_data: dict[str, list[str] | np.ndarray], featu
 
 
 def _assert_type_and_shape(stats_list: list[dict[str, dict]]):
-    for i in range(len(stats_list)):
+    for i in enumerate(stats_list):
         for fkey in stats_list[i]:
             for k, v in stats_list[i][fkey].items():
                 if not isinstance(v, np.ndarray):
diff --git a/lerobot/common/datasets/factory.py b/lerobot/common/datasets/factory.py
index 38c01b42f..2e72d2bc2 100644
--- a/lerobot/common/datasets/factory.py
+++ b/lerobot/common/datasets/factory.py
@@ -13,8 +13,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import logging
-from pprint import pformat
 
 import torch
 
@@ -98,17 +96,17 @@ def make_dataset(cfg: TrainPipelineConfig) -> LeRobotDataset | MultiLeRobotDatas
         )
     else:
         raise NotImplementedError("The MultiLeRobotDataset isn't supported for now.")
-        dataset = MultiLeRobotDataset(
-            cfg.dataset.repo_id,
-            # TODO(aliberts): add proper support for multi dataset
-            # delta_timestamps=delta_timestamps,
-            image_transforms=image_transforms,
-            video_backend=cfg.dataset.video_backend,
-        )
-        logging.info(
-            "Multiple datasets were provided. Applied the following index mapping to the provided datasets: "
-            f"{pformat(dataset.repo_id_to_index, indent=2)}"
-        )
+        # dataset = MultiLeRobotDataset(
+        #     cfg.dataset.repo_id,
+        #     # TODO(aliberts): add proper support for multi dataset
+        #     # delta_timestamps=delta_timestamps,
+        #     image_transforms=image_transforms,
+        #     video_backend=cfg.dataset.video_backend,
+        # )
+        # logging.info(
+        #     "Multiple datasets were provided. Applied the following index mapping to the provided datasets: "
+        #     f"{pformat(dataset.repo_id_to_index, indent=2)}"
+        # )
 
     if cfg.dataset.use_imagenet_stats:
         for key in dataset.meta.camera_keys:
diff --git a/lerobot/common/datasets/image_writer.py b/lerobot/common/datasets/image_writer.py
index 6fc0ee2f8..fbbe4fcfe 100644
--- a/lerobot/common/datasets/image_writer.py
+++ b/lerobot/common/datasets/image_writer.py
@@ -81,21 +81,21 @@ def write_image(image: np.ndarray | PIL.Image.Image, fpath: Path):
         print(f"Error writing image {fpath}: {e}")
 
 
-def worker_thread_loop(queue: queue.Queue):
+def worker_thread_loop(task_queue: queue.Queue):
     while True:
-        item = queue.get()
+        item = task_queue.get()
         if item is None:
-            queue.task_done()
+            task_queue.task_done()
             break
         image_array, fpath = item
         write_image(image_array, fpath)
-        queue.task_done()
+        task_queue.task_done()
 
 
-def worker_process(queue: queue.Queue, num_threads: int):
+def worker_process(task_queue: queue.Queue, num_threads: int):
     threads = []
     for _ in range(num_threads):
-        t = threading.Thread(target=worker_thread_loop, args=(queue,))
+        t = threading.Thread(target=worker_thread_loop, args=(task_queue,))
         t.daemon = True
         t.start()
         threads.append(t)
diff --git a/lerobot/common/datasets/lerobot_dataset.py b/lerobot/common/datasets/lerobot_dataset.py
index 5414c76df..68c14be8a 100644
--- a/lerobot/common/datasets/lerobot_dataset.py
+++ b/lerobot/common/datasets/lerobot_dataset.py
@@ -87,6 +87,7 @@ class LeRobotDatasetMetadata:
         self.repo_id = repo_id
         self.revision = revision if revision else CODEBASE_VERSION
         self.root = Path(root) if root is not None else HF_LEROBOT_HOME / repo_id
+        self.stats = None
 
         try:
             if force_cache_sync:
@@ -102,10 +103,10 @@ class LeRobotDatasetMetadata:
 
     def load_metadata(self):
         self.info = load_info(self.root)
-        check_version_compatibility(self.repo_id, self._version, CODEBASE_VERSION)
+        check_version_compatibility(self.repo_id, self.version, CODEBASE_VERSION)
         self.tasks, self.task_to_task_index = load_tasks(self.root)
         self.episodes = load_episodes(self.root)
-        if self._version < packaging.version.parse("v2.1"):
+        if self.version < packaging.version.parse("v2.1"):
             self.stats = load_stats(self.root)
             self.episodes_stats = backward_compatible_episodes_stats(self.stats, self.episodes)
         else:
@@ -127,7 +128,7 @@ class LeRobotDatasetMetadata:
         )
 
     @property
-    def _version(self) -> packaging.version.Version:
+    def version(self) -> packaging.version.Version:
         """Codebase version used to create this dataset."""
         return packaging.version.parse(self.info["codebase_version"])
 
@@ -321,8 +322,9 @@ class LeRobotDatasetMetadata:
             robot_type = robot.robot_type
             if not all(cam.fps == fps for cam in robot.cameras.values()):
                 logging.warning(
-                    f"Some cameras in your {robot.robot_type} robot don't have an fps matching the fps of your dataset."
-                    "In this case, frames from lower fps cameras will be repeated to fill in the blanks."
+                    "Some cameras in your %s robot don't have an fps matching the fps of your dataset."
+                    "In this case, frames from lower fps cameras will be repeated to fill in the blanks.",
+                    robot.robot_type,
                 )
         elif features is None:
             raise ValueError(
@@ -486,7 +488,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         self.meta = LeRobotDatasetMetadata(
             self.repo_id, self.root, self.revision, force_cache_sync=force_cache_sync
         )
-        if self.episodes is not None and self.meta._version >= packaging.version.parse("v2.1"):
+        if self.episodes is not None and self.meta.version >= packaging.version.parse("v2.1"):
             episodes_stats = [self.meta.episodes_stats[ep_idx] for ep_idx in self.episodes]
             self.stats = aggregate_stats(episodes_stats)
 
@@ -518,7 +520,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         self,
         branch: str | None = None,
         tags: list | None = None,
-        license: str | None = "apache-2.0",
+        dataset_license: str | None = "apache-2.0",
         tag_version: bool = True,
         push_videos: bool = True,
         private: bool = False,
@@ -561,7 +563,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
 
         if not hub_api.file_exists(self.repo_id, REPOCARD_NAME, repo_type="dataset", revision=branch):
             card = create_lerobot_dataset_card(
-                tags=tags, dataset_info=self.meta.info, license=license, **card_kwargs
+                tags=tags, dataset_info=self.meta.info, license=dataset_license, **card_kwargs
             )
             card.push_to_hub(repo_id=self.repo_id, repo_type="dataset", revision=branch)
 
@@ -842,6 +844,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
                 save the current episode in self.episode_buffer, which is filled with 'add_frame'. Defaults to
                 None.
         """
+        episode_buffer = None
         if not episode_data:
             episode_buffer = self.episode_buffer
 
@@ -1086,8 +1089,9 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
         for repo_id, ds in zip(self.repo_ids, self._datasets, strict=True):
             extra_keys = set(ds.features).difference(intersection_features)
             logging.warning(
-                f"keys {extra_keys} of {repo_id} were disabled as they are not contained in all the "
-                "other datasets."
+                "keys %s of %s were disabled as they are not contained in all the other datasets.",
+                extra_keys,
+                repo_id,
             )
             self.disabled_features.update(extra_keys)
 
diff --git a/lerobot/common/datasets/push_dataset_to_hub/_diffusion_policy_replay_buffer.py b/lerobot/common/datasets/push_dataset_to_hub/_diffusion_policy_replay_buffer.py
index 33b4c9745..ec3f1379c 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/_diffusion_policy_replay_buffer.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/_diffusion_policy_replay_buffer.py
@@ -53,7 +53,7 @@ def rechunk_recompress_array(group, name, chunks=None, chunk_length=None, compre
     # rechunk recompress
     group.move(name, tmp_key)
     old_arr = group[tmp_key]
-    n_copied, n_skipped, n_bytes_copied = zarr.copy(
+    _n_copied, _n_skipped, _n_bytes_copied = zarr.copy(
         source=old_arr,
         dest=group,
         name=name,
@@ -192,7 +192,7 @@ class ReplayBuffer:
         else:
             root = zarr.group(store=store)
             # copy without recompression
-            n_copied, n_skipped, n_bytes_copied = zarr.copy_store(
+            _n_copied, _n_skipped, _n_bytes_copied = zarr.copy_store(
                 source=src_store, dest=store, source_path="/meta", dest_path="/meta", if_exists=if_exists
             )
             data_group = root.create_group("data", overwrite=True)
@@ -205,7 +205,7 @@ class ReplayBuffer:
                 if cks == value.chunks and cpr == value.compressor:
                     # copy without recompression
                     this_path = "/data/" + key
-                    n_copied, n_skipped, n_bytes_copied = zarr.copy_store(
+                    _n_copied, _n_skipped, _n_bytes_copied = zarr.copy_store(
                         source=src_store,
                         dest=store,
                         source_path=this_path,
@@ -214,7 +214,7 @@ class ReplayBuffer:
                     )
                 else:
                     # copy with recompression
-                    n_copied, n_skipped, n_bytes_copied = zarr.copy(
+                    _n_copied, _n_skipped, _n_bytes_copied = zarr.copy(
                         source=value,
                         dest=data_group,
                         name=key,
@@ -275,7 +275,7 @@ class ReplayBuffer:
             compressors = {}
         if self.backend == "zarr":
             # recompression free copy
-            n_copied, n_skipped, n_bytes_copied = zarr.copy_store(
+            _n_copied, _n_skipped, _n_bytes_copied = zarr.copy_store(
                 source=self.root.store,
                 dest=store,
                 source_path="/meta",
@@ -297,7 +297,7 @@ class ReplayBuffer:
                 if cks == value.chunks and cpr == value.compressor:
                     # copy without recompression
                     this_path = "/data/" + key
-                    n_copied, n_skipped, n_bytes_copied = zarr.copy_store(
+                    _n_copied, _n_skipped, _n_bytes_copied = zarr.copy_store(
                         source=self.root.store,
                         dest=store,
                         source_path=this_path,
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 cc291ceab..285d19424 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/_download_raw.py
@@ -162,9 +162,9 @@ 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}")
+    logging.info("Start downloading from huggingface.co/%s for %s", user_id, dataset_id)
     snapshot_download(repo_id, repo_type="dataset", local_dir=raw_dir)
-    logging.info(f"Finish downloading from huggingface.co/{user_id} for {dataset_id}")
+    logging.info("Finish downloading from huggingface.co/%s for %s", user_id, dataset_id)
 
 
 def download_all_raw_datasets(data_dir: Path | None = None):
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 e2973ef81..e80eb54d6 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
@@ -72,7 +72,7 @@ def check_format(raw_dir) -> bool:
                     assert data[f"/observations/images/{camera}"].ndim == 2
                 else:
                     assert data[f"/observations/images/{camera}"].ndim == 4
-                    b, h, w, c = data[f"/observations/images/{camera}"].shape
+                    _, h, w, c = data[f"/observations/images/{camera}"].shape
                     assert c < h and c < w, f"Expect (h,w,c) image format but ({h=},{w=},{c=}) provided."
 
 
@@ -103,6 +103,7 @@ def load_from_raw(
 
             state = torch.from_numpy(ep["/observations/qpos"][:])
             action = torch.from_numpy(ep["/action"][:])
+            velocity = None
             if "/observations/qvel" in ep:
                 velocity = torch.from_numpy(ep["/observations/qvel"][:])
             if "/observations/effort" in ep:
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 264925766..df1a49dcf 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
@@ -96,6 +96,7 @@ def from_raw_to_lerobot_format(
     if fps is None:
         fps = 30
 
+    # TODO(Steven): Is this meant to call cam_png_format.load_from_raw?
     data_dict = load_from_raw(raw_dir, videos_dir, fps, video, episodes)
     hf_dataset = to_hf_dataset(data_dict, video)
     episode_data_index = calculate_episode_data_index(hf_dataset)
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 acf820bf4..ca0b846ae 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
@@ -42,7 +42,9 @@ def check_format(raw_dir) -> bool:
     return True
 
 
-def load_from_raw(raw_dir: Path, videos_dir: Path, fps: int, video: bool, episodes: list[int] | None = None):
+def load_from_raw(
+    raw_dir: Path, videos_dir: Path, fps: int, _video: bool, _episodes: list[int] | None = None
+):
     # Load data stream that will be used as reference for the timestamps synchronization
     reference_files = list(raw_dir.glob("observation.images.cam_*.parquet"))
     if len(reference_files) == 0:
diff --git a/lerobot/common/datasets/push_dataset_to_hub/utils.py b/lerobot/common/datasets/push_dataset_to_hub/utils.py
index ebcf87f77..70650953a 100644
--- a/lerobot/common/datasets/push_dataset_to_hub/utils.py
+++ b/lerobot/common/datasets/push_dataset_to_hub/utils.py
@@ -55,7 +55,7 @@ def save_images_concurrently(imgs_array: numpy.array, out_dir: Path, max_workers
 
     num_images = len(imgs_array)
     with ThreadPoolExecutor(max_workers=max_workers) as executor:
-        [executor.submit(save_image, imgs_array[i], i, out_dir) for i in range(num_images)]
+        _ = [executor.submit(save_image, imgs_array[i], i, out_dir) for i in range(num_images)]
 
 
 def get_default_encoding() -> dict:
@@ -92,24 +92,23 @@ def calculate_episode_data_index(hf_dataset: datasets.Dataset) -> Dict[str, torc
     episode_data_index = {"from": [], "to": []}
 
     current_episode = None
-    """
-    The episode_index is a list of integers, each representing the episode index of the corresponding example.
-    For instance, the following is a valid episode_index:
-      [0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2]
-
-    Below, we iterate through the episode_index and populate the episode_data_index dictionary with the starting and
-    ending index of each episode. For the episode_index above, the episode_data_index dictionary will look like this:
-        {
-            "from": [0, 3, 7],
-            "to": [3, 7, 12]
-        }
-    """
+    # The episode_index is a list of integers, each representing the episode index of the corresponding example.
+    # For instance, the following is a valid episode_index:
+    #   [0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2]
+    #
+    # Below, we iterate through the episode_index and populate the episode_data_index dictionary with the starting and
+    # ending index of each episode. For the episode_index above, the episode_data_index dictionary will look like this:
+    #     {
+    #         "from": [0, 3, 7],
+    #         "to": [3, 7, 12]
+    #     }
     if len(hf_dataset) == 0:
         episode_data_index = {
             "from": torch.tensor([]),
             "to": torch.tensor([]),
         }
         return episode_data_index
+    idx = None
     for idx, episode_idx in enumerate(hf_dataset["episode_index"]):
         if episode_idx != current_episode:
             # We encountered a new episode, so we append its starting location to the "from" list
diff --git a/lerobot/common/datasets/transforms.py b/lerobot/common/datasets/transforms.py
index 720c939b8..36166e21e 100644
--- a/lerobot/common/datasets/transforms.py
+++ b/lerobot/common/datasets/transforms.py
@@ -23,6 +23,7 @@ from torchvision.transforms.v2 import Transform
 from torchvision.transforms.v2 import functional as F  # noqa: N812
 
 
+# TODO(Steven): Missing transform() implementation
 class RandomSubsetApply(Transform):
     """Apply a random subset of N transformations from a list of transformations.
 
@@ -218,6 +219,7 @@ def make_transform_from_config(cfg: ImageTransformConfig):
         raise ValueError(f"Transform '{cfg.type}' is not valid.")
 
 
+# TODO(Steven): Missing transform() implementation
 class ImageTransforms(Transform):
     """A class to compose image transforms based on configuration."""
 
diff --git a/lerobot/common/datasets/utils.py b/lerobot/common/datasets/utils.py
index 7e297b350..4b3a5d173 100644
--- a/lerobot/common/datasets/utils.py
+++ b/lerobot/common/datasets/utils.py
@@ -135,21 +135,21 @@ def serialize_dict(stats: dict[str, torch.Tensor | np.ndarray | dict]) -> dict:
 
 def embed_images(dataset: datasets.Dataset) -> datasets.Dataset:
     # Embed image bytes into the table before saving to parquet
-    format = dataset.format
+    ds_format = dataset.format
     dataset = dataset.with_format("arrow")
     dataset = dataset.map(embed_table_storage, batched=False)
-    dataset = dataset.with_format(**format)
+    dataset = dataset.with_format(**ds_format)
     return dataset
 
 
 def load_json(fpath: Path) -> Any:
-    with open(fpath) as f:
+    with open(fpath, encoding="utf-8") as f:
         return json.load(f)
 
 
 def write_json(data: dict, fpath: Path) -> None:
     fpath.parent.mkdir(exist_ok=True, parents=True)
-    with open(fpath, "w") as f:
+    with open(fpath, "w", encoding="utf-8") as f:
         json.dump(data, f, indent=4, ensure_ascii=False)
 
 
@@ -300,7 +300,7 @@ def check_version_compatibility(
     if v_check.major < v_current.major and enforce_breaking_major:
         raise BackwardCompatibilityError(repo_id, v_check)
     elif v_check.minor < v_current.minor:
-        logging.warning(V21_MESSAGE.format(repo_id=repo_id, version=v_check))
+        logging.warning("%s", V21_MESSAGE.format(repo_id=repo_id, version=v_check))
 
 
 def get_repo_versions(repo_id: str) -> list[packaging.version.Version]:
@@ -348,7 +348,9 @@ def get_safe_version(repo_id: str, version: str | packaging.version.Version) ->
     if compatibles:
         return_version = max(compatibles)
         if return_version < target_version:
-            logging.warning(f"Revision {version} for {repo_id} not found, using version v{return_version}")
+            logging.warning(
+                "Revision %s for %s not found, using version v%s", version, repo_id, return_version
+            )
         return f"v{return_version}"
 
     lower_major = [v for v in hub_versions if v.major < target_version.major]
@@ -403,7 +405,7 @@ def dataset_to_policy_features(features: dict[str, dict]) -> dict[str, PolicyFea
     for key, ft in features.items():
         shape = ft["shape"]
         if ft["dtype"] in ["image", "video"]:
-            type = FeatureType.VISUAL
+            feature_type = FeatureType.VISUAL
             if len(shape) != 3:
                 raise ValueError(f"Number of dimensions of {key} != 3 (shape={shape})")
 
@@ -412,16 +414,16 @@ def dataset_to_policy_features(features: dict[str, dict]) -> dict[str, PolicyFea
             if names[2] in ["channel", "channels"]:  # (h, w, c) -> (c, h, w)
                 shape = (shape[2], shape[0], shape[1])
         elif key == "observation.environment_state":
-            type = FeatureType.ENV
+            feature_type = FeatureType.ENV
         elif key.startswith("observation"):
-            type = FeatureType.STATE
+            feature_type = FeatureType.STATE
         elif key == "action":
-            type = FeatureType.ACTION
+            feature_type = FeatureType.ACTION
         else:
             continue
 
         policy_features[key] = PolicyFeature(
-            type=type,
+            type=feature_type,
             shape=shape,
         )
 
diff --git a/lerobot/common/datasets/v2/batch_convert_dataset_v1_to_v2.py b/lerobot/common/datasets/v2/batch_convert_dataset_v1_to_v2.py
index 99ab2cbf6..e8b8e8f14 100644
--- a/lerobot/common/datasets/v2/batch_convert_dataset_v1_to_v2.py
+++ b/lerobot/common/datasets/v2/batch_convert_dataset_v1_to_v2.py
@@ -871,11 +871,11 @@ def batch_convert():
         try:
             convert_dataset(repo_id, LOCAL_DIR, **kwargs)
             status = f"{repo_id}: success."
-            with open(logfile, "a") as file:
+            with open(logfile, "a", encoding="utf-8") as file:
                 file.write(status + "\n")
         except Exception:
             status = f"{repo_id}: failed\n    {traceback.format_exc()}"
-            with open(logfile, "a") as file:
+            with open(logfile, "a", encoding="utf-8") as file:
                 file.write(status + "\n")
             continue
 
diff --git a/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py b/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
index acf0282fc..a3e5dacff 100644
--- a/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
+++ b/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
@@ -190,11 +190,11 @@ def convert_stats_to_json(v1_dir: Path, v2_dir: Path) -> None:
 
     json_path = v2_dir / STATS_PATH
     json_path.parent.mkdir(exist_ok=True, parents=True)
-    with open(json_path, "w") as f:
+    with open(json_path, "w", encoding="utf-8") as f:
         json.dump(serialized_stats, f, indent=4)
 
     # Sanity check
-    with open(json_path) as f:
+    with open(json_path, encoding="utf-8") as f:
         stats_json = json.load(f)
 
     stats_json = flatten_dict(stats_json)
@@ -213,7 +213,7 @@ def get_features_from_hf_dataset(
             dtype = ft.dtype
             shape = (1,)
             names = None
-        if isinstance(ft, datasets.Sequence):
+        elif isinstance(ft, datasets.Sequence):
             assert isinstance(ft.feature, datasets.Value)
             dtype = ft.feature.dtype
             shape = (ft.length,)
@@ -232,6 +232,8 @@ def get_features_from_hf_dataset(
             dtype = "video"
             shape = None  # Add shape later
             names = ["height", "width", "channels"]
+        else:
+            raise NotImplementedError(f"Feature type {ft._type} not supported.")
 
         features[key] = {
             "dtype": dtype,
@@ -358,9 +360,9 @@ def move_videos(
                 if len(video_dirs) == 1:
                     video_path = video_dirs[0] / video_file
                 else:
-                    for dir in video_dirs:
-                        if (dir / video_file).is_file():
-                            video_path = dir / video_file
+                    for v_dir in video_dirs:
+                        if (v_dir / video_file).is_file():
+                            video_path = v_dir / video_file
                             break
 
                 video_path.rename(work_dir / target_path)
@@ -652,6 +654,7 @@ def main():
     if not args.local_dir:
         args.local_dir = Path("/tmp/lerobot_dataset_v2")
 
+    robot_config = None
     if args.robot is not None:
         robot_config = make_robot_config(args.robot)
 
diff --git a/lerobot/common/datasets/v21/_remove_language_instruction.py b/lerobot/common/datasets/v21/_remove_language_instruction.py
index 643ddd3f2..7832ef75a 100644
--- a/lerobot/common/datasets/v21/_remove_language_instruction.py
+++ b/lerobot/common/datasets/v21/_remove_language_instruction.py
@@ -50,7 +50,7 @@ def fix_dataset(repo_id: str) -> str:
         return f"{repo_id}: skipped (no diff)"
 
     if diff_meta_parquet:
-        logging.warning(f"In info.json not in parquet: {meta_features - parquet_features}")
+        logging.warning("In info.json not in parquet: %s", meta_features - parquet_features)
         assert diff_meta_parquet == {"language_instruction"}
         lerobot_metadata.features.pop("language_instruction")
         write_info(lerobot_metadata.info, lerobot_metadata.root)
@@ -79,7 +79,7 @@ def batch_fix():
             status = f"{repo_id}: failed\n    {traceback.format_exc()}"
 
         logging.info(status)
-        with open(logfile, "a") as file:
+        with open(logfile, "a", encoding="utf-8") as file:
             file.write(status + "\n")
 
 
diff --git a/lerobot/common/datasets/v21/batch_convert_dataset_v20_to_v21.py b/lerobot/common/datasets/v21/batch_convert_dataset_v20_to_v21.py
index cc9272a83..ae2446219 100644
--- a/lerobot/common/datasets/v21/batch_convert_dataset_v20_to_v21.py
+++ b/lerobot/common/datasets/v21/batch_convert_dataset_v20_to_v21.py
@@ -46,7 +46,7 @@ def batch_convert():
         except Exception:
             status = f"{repo_id}: failed\n    {traceback.format_exc()}"
 
-        with open(logfile, "a") as file:
+        with open(logfile, "a", encoding="utf-8") as file:
             file.write(status + "\n")
 
 
diff --git a/lerobot/common/datasets/v21/convert_dataset_v20_to_v21.py b/lerobot/common/datasets/v21/convert_dataset_v20_to_v21.py
index 176d16d0f..9b40b8897 100644
--- a/lerobot/common/datasets/v21/convert_dataset_v20_to_v21.py
+++ b/lerobot/common/datasets/v21/convert_dataset_v20_to_v21.py
@@ -45,6 +45,9 @@ V21 = "v2.1"
 
 
 class SuppressWarnings:
+    def __init__(self):
+        self.previous_level = None
+
     def __enter__(self):
         self.previous_level = logging.getLogger().getEffectiveLevel()
         logging.getLogger().setLevel(logging.ERROR)
diff --git a/lerobot/common/datasets/video_utils.py b/lerobot/common/datasets/video_utils.py
index 9f043f966..de02127a2 100644
--- a/lerobot/common/datasets/video_utils.py
+++ b/lerobot/common/datasets/video_utils.py
@@ -83,7 +83,7 @@ def decode_video_frames_torchvision(
     for frame in reader:
         current_ts = frame["pts"]
         if log_loaded_timestamps:
-            logging.info(f"frame loaded at timestamp={current_ts:.4f}")
+            logging.info("frame loaded at timestamp=%.4f", current_ts)
         loaded_frames.append(frame["data"])
         loaded_ts.append(current_ts)
         if current_ts >= last_ts:
@@ -118,7 +118,7 @@ def decode_video_frames_torchvision(
     closest_ts = loaded_ts[argmin_]
 
     if log_loaded_timestamps:
-        logging.info(f"{closest_ts=}")
+        logging.info("closest_ts=%s", closest_ts)
 
     # convert to the pytorch format which is float32 in [0,1] range (and channel first)
     closest_frames = closest_frames.type(torch.float32) / 255
@@ -227,7 +227,9 @@ def get_audio_info(video_path: Path | str) -> dict:
         "json",
         str(video_path),
     ]
-    result = subprocess.run(ffprobe_audio_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    result = subprocess.run(
+        ffprobe_audio_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True, check=True
+    )
     if result.returncode != 0:
         raise RuntimeError(f"Error running ffprobe: {result.stderr}")
 
@@ -263,7 +265,9 @@ def get_video_info(video_path: Path | str) -> dict:
         "json",
         str(video_path),
     ]
-    result = subprocess.run(ffprobe_video_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    result = subprocess.run(
+        ffprobe_video_cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True, check=True
+    )
     if result.returncode != 0:
         raise RuntimeError(f"Error running ffprobe: {result.stderr}")