diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cb9055266..d34a93c9a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,7 +21,12 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11"]
-
+        include:
+          # Default version
+          - gymnasium-version: "1.0.0"
+          # Add a new config to test gym<1.0
+          - python-version: "3.10"
+            gymnasium-version: "0.29.1"
     steps:
       - uses: actions/checkout@v3
       - name: Set up Python ${{ matrix.python-version }}
@@ -37,15 +42,14 @@ jobs:
           # See https://github.com/astral-sh/uv/issues/1497
           uv pip install --system torch==2.3.1+cpu --index https://download.pytorch.org/whl/cpu
 
-          # Install Atari Roms
-          uv pip install --system autorom
-          wget https://gist.githubusercontent.com/jjshoots/61b22aefce4456920ba99f2c36906eda/raw/00046ac3403768bfe45857610a3d333b8e35e026/Roms.tar.gz.b64
-          base64 Roms.tar.gz.b64 --decode &> Roms.tar.gz
-          AutoROM --accept-license --source-file Roms.tar.gz
-
-          uv pip install --system .[extra_no_roms,tests,docs]
+          uv pip install --system .[extra,tests,docs]
           # Use headless version
           uv pip install --system opencv-python-headless
+      - name: Install specific version of gym
+        run: |
+          uv pip install --system gymnasium==${{ matrix.gymnasium-version }}
+        # Only run for python 3.10, downgrade gym to 0.29.1
+        if: matrix.gymnasium-version != '1.0.0'
       - name: Lint with ruff
         run: |
           make lint
diff --git a/docs/conda_env.yml b/docs/conda_env.yml
index e025a57e1..ac065b3b9 100644
--- a/docs/conda_env.yml
+++ b/docs/conda_env.yml
@@ -8,7 +8,7 @@ dependencies:
   - python=3.11
   - pytorch=2.5.0=py3.11_cpu_0
   - pip:
-    - gymnasium>=0.28.1,<0.30
+    - gymnasium>=0.29.1,<1.1.0
     - cloudpickle
     - opencv-python-headless
     - pandas
diff --git a/docs/misc/changelog.rst b/docs/misc/changelog.rst
index b32cd7ce1..cf2a2a520 100644
--- a/docs/misc/changelog.rst
+++ b/docs/misc/changelog.rst
@@ -3,10 +3,10 @@
 Changelog
 ==========
 
-Release 2.4.0a10 (WIP)
+Release 2.4.0a11 (WIP)
 --------------------------
 
-**New algorithm: CrossQ in SB3 Contrib**
+**New algorithm: CrossQ in SB3 Contrib, Gymnasium v1.0 support**
 
 .. note::
 
@@ -24,12 +24,14 @@ Release 2.4.0a10 (WIP)
 
 Breaking Changes:
 ^^^^^^^^^^^^^^^^^
+- Increase minimum required version of Gymnasium to 0.29.1
 
 New Features:
 ^^^^^^^^^^^^^
 - Added support for ``pre_linear_modules`` and ``post_linear_modules`` in ``create_mlp`` (useful for adding normalization layers, like in DroQ or CrossQ)
 - Enabled np.ndarray logging for TensorBoardOutputFormat as histogram (see GH#1634) (@iwishwasaneagle)
 - Updated env checker to warn users when using multi-dim array to define `MultiDiscrete` spaces
+- Added support for Gymnasium v1.0
 
 Bug Fixes:
 ^^^^^^^^^^
@@ -69,6 +71,7 @@ Others:
 - Added a warning to recommend using CPU with on policy algorithms (A2C/PPO) and ``MlpPolicy``
 - Switched to uv to download packages faster on GitHub CI
 - Updated dependencies for read the doc
+- Removed unnecessary ``copy_obs_dict`` method for ``SubprocVecEnv``, remove the use of ordered dict and rename ``flatten_obs`` to ``stack_obs``
 
 Bug Fixes:
 ^^^^^^^^^^
diff --git a/pyproject.toml b/pyproject.toml
index dd435a33e..1fd1a1890 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,6 @@ ignore = ["B028", "RUF013"]
 # ClassVar, implicit optional check not needed for tests
 "./tests/*.py" = ["RUF012", "RUF013"]
 
-
 [tool.ruff.lint.mccabe]
 # Unlike Flake8, default to a complexity level of 10.
 max-complexity = 15
diff --git a/setup.py b/setup.py
index 9d56dfd77..52f626462 100644
--- a/setup.py
+++ b/setup.py
@@ -70,37 +70,13 @@
 
 """  # noqa:E501
 
-# Atari Games download is sometimes problematic:
-# https://github.com/Farama-Foundation/AutoROM/issues/39
-# That's why we define extra packages without it.
-extra_no_roms = [
-    # For render
-    "opencv-python",
-    "pygame",
-    # Tensorboard support
-    "tensorboard>=2.9.1",
-    # Checking memory taken by replay buffer
-    "psutil",
-    # For progress bar callback
-    "tqdm",
-    "rich",
-    # For atari games,
-    "shimmy[atari]~=1.3.0",
-    "pillow",
-]
-
-extra_packages = extra_no_roms + [  # noqa: RUF005
-    # For atari roms,
-    "autorom[accept-rom-license]~=0.6.1",
-]
-
 
 setup(
     name="stable_baselines3",
     packages=[package for package in find_packages() if package.startswith("stable_baselines3")],
     package_data={"stable_baselines3": ["py.typed", "version.txt"]},
     install_requires=[
-        "gymnasium>=0.28.1,<0.30",
+        "gymnasium>=0.29.1,<1.1.0",
         "numpy>=1.20,<2.0",  # PyTorch not compatible https://github.com/pytorch/pytorch/issues/107302
         "torch>=1.13",
         # For saving models
@@ -133,8 +109,21 @@
             # Copy button for code snippets
             "sphinx_copybutton",
         ],
-        "extra": extra_packages,
-        "extra_no_roms": extra_no_roms,
+        "extra": [
+            # For render
+            "opencv-python",
+            "pygame",
+            # Tensorboard support
+            "tensorboard>=2.9.1",
+            # Checking memory taken by replay buffer
+            "psutil",
+            # For progress bar callback
+            "tqdm",
+            "rich",
+            # For atari games,
+            "ale-py>=0.9.0",
+            "pillow",
+        ],
     },
     description="Pytorch version of Stable Baselines, implementations of reinforcement learning algorithms.",
     author="Antonin Raffin",
diff --git a/stable_baselines3/common/vec_env/dummy_vec_env.py b/stable_baselines3/common/vec_env/dummy_vec_env.py
index 15ecfb681..5625e2453 100644
--- a/stable_baselines3/common/vec_env/dummy_vec_env.py
+++ b/stable_baselines3/common/vec_env/dummy_vec_env.py
@@ -8,7 +8,7 @@
 
 from stable_baselines3.common.vec_env.base_vec_env import VecEnv, VecEnvIndices, VecEnvObs, VecEnvStepReturn
 from stable_baselines3.common.vec_env.patch_gym import _patch_env
-from stable_baselines3.common.vec_env.util import copy_obs_dict, dict_to_obs, obs_space_info
+from stable_baselines3.common.vec_env.util import dict_to_obs, obs_space_info
 
 
 class DummyVecEnv(VecEnv):
@@ -110,12 +110,12 @@ def _save_obs(self, env_idx: int, obs: VecEnvObs) -> None:
                 self.buf_obs[key][env_idx] = obs[key]  # type: ignore[call-overload]
 
     def _obs_from_buf(self) -> VecEnvObs:
-        return dict_to_obs(self.observation_space, copy_obs_dict(self.buf_obs))
+        return dict_to_obs(self.observation_space, deepcopy(self.buf_obs))
 
     def get_attr(self, attr_name: str, indices: VecEnvIndices = None) -> List[Any]:
         """Return attribute from vectorized environment (see base class)."""
         target_envs = self._get_target_envs(indices)
-        return [getattr(env_i, attr_name) for env_i in target_envs]
+        return [env_i.get_wrapper_attr(attr_name) for env_i in target_envs]
 
     def set_attr(self, attr_name: str, value: Any, indices: VecEnvIndices = None) -> None:
         """Set attribute inside vectorized environments (see base class)."""
@@ -126,7 +126,7 @@ def set_attr(self, attr_name: str, value: Any, indices: VecEnvIndices = None) ->
     def env_method(self, method_name: str, *method_args, indices: VecEnvIndices = None, **method_kwargs) -> List[Any]:
         """Call instance methods of vectorized environments."""
         target_envs = self._get_target_envs(indices)
-        return [getattr(env_i, method_name)(*method_args, **method_kwargs) for env_i in target_envs]
+        return [env_i.get_wrapper_attr(method_name)(*method_args, **method_kwargs) for env_i in target_envs]
 
     def env_is_wrapped(self, wrapper_class: Type[gym.Wrapper], indices: VecEnvIndices = None) -> List[bool]:
         """Check if worker environments are wrapped with a given wrapper"""
diff --git a/stable_baselines3/common/vec_env/patch_gym.py b/stable_baselines3/common/vec_env/patch_gym.py
index 6ba655ebf..874809a03 100644
--- a/stable_baselines3/common/vec_env/patch_gym.py
+++ b/stable_baselines3/common/vec_env/patch_gym.py
@@ -43,7 +43,7 @@ def _patch_env(env: Union["gym.Env", gymnasium.Env]) -> gymnasium.Env:  # pragma
             "Missing shimmy installation. You provided an OpenAI Gym environment. "
             "Stable-Baselines3 (SB3) has transitioned to using Gymnasium internally. "
             "In order to use OpenAI Gym environments with SB3, you need to "
-            "install shimmy (`pip install 'shimmy>=0.2.1'`)."
+            "install shimmy (`pip install 'shimmy>=2.0'`)."
         ) from e
 
     warnings.warn(
diff --git a/stable_baselines3/common/vec_env/subproc_vec_env.py b/stable_baselines3/common/vec_env/subproc_vec_env.py
index c598c735a..a606a7cb9 100644
--- a/stable_baselines3/common/vec_env/subproc_vec_env.py
+++ b/stable_baselines3/common/vec_env/subproc_vec_env.py
@@ -1,6 +1,5 @@
 import multiprocessing as mp
 import warnings
-from collections import OrderedDict
 from typing import Any, Callable, Dict, List, Optional, Sequence, Tuple, Type, Union
 
 import gymnasium as gym
@@ -54,10 +53,10 @@ def _worker(
             elif cmd == "get_spaces":
                 remote.send((env.observation_space, env.action_space))
             elif cmd == "env_method":
-                method = getattr(env, data[0])
+                method = env.get_wrapper_attr(data[0])
                 remote.send(method(*data[1], **data[2]))
             elif cmd == "get_attr":
-                remote.send(getattr(env, data))
+                remote.send(env.get_wrapper_attr(data))
             elif cmd == "set_attr":
                 remote.send(setattr(env, data[0], data[1]))  # type: ignore[func-returns-value]
             elif cmd == "is_wrapped":
@@ -129,7 +128,7 @@ def step_wait(self) -> VecEnvStepReturn:
         results = [remote.recv() for remote in self.remotes]
         self.waiting = False
         obs, rews, dones, infos, self.reset_infos = zip(*results)  # type: ignore[assignment]
-        return _flatten_obs(obs, self.observation_space), np.stack(rews), np.stack(dones), infos  # type: ignore[return-value]
+        return _stack_obs(obs, self.observation_space), np.stack(rews), np.stack(dones), infos  # type: ignore[return-value]
 
     def reset(self) -> VecEnvObs:
         for env_idx, remote in enumerate(self.remotes):
@@ -139,7 +138,7 @@ def reset(self) -> VecEnvObs:
         # Seeds and options are only used once
         self._reset_seeds()
         self._reset_options()
-        return _flatten_obs(obs, self.observation_space)
+        return _stack_obs(obs, self.observation_space)
 
     def close(self) -> None:
         if self.closed:
@@ -206,27 +205,28 @@ def _get_target_remotes(self, indices: VecEnvIndices) -> List[Any]:
         return [self.remotes[i] for i in indices]
 
 
-def _flatten_obs(obs: Union[List[VecEnvObs], Tuple[VecEnvObs]], space: spaces.Space) -> VecEnvObs:
+def _stack_obs(obs_list: Union[List[VecEnvObs], Tuple[VecEnvObs]], space: spaces.Space) -> VecEnvObs:
     """
-    Flatten observations, depending on the observation space.
+    Stack observations (convert from a list of single env obs to a stack of obs),
+    depending on the observation space.
 
     :param obs: observations.
                 A list or tuple of observations, one per environment.
                 Each environment observation may be a NumPy array, or a dict or tuple of NumPy arrays.
-    :return: flattened observations.
-            A flattened NumPy array or an OrderedDict or tuple of flattened numpy arrays.
+    :return: Concatenated observations.
+            A NumPy array or a dict or tuple of stacked numpy arrays.
             Each NumPy array has the environment index as its first axis.
     """
-    assert isinstance(obs, (list, tuple)), "expected list or tuple of observations per environment"
-    assert len(obs) > 0, "need observations from at least one environment"
+    assert isinstance(obs_list, (list, tuple)), "expected list or tuple of observations per environment"
+    assert len(obs_list) > 0, "need observations from at least one environment"
 
     if isinstance(space, spaces.Dict):
-        assert isinstance(space.spaces, OrderedDict), "Dict space must have ordered subspaces"
-        assert isinstance(obs[0], dict), "non-dict observation for environment with Dict observation space"
-        return OrderedDict([(k, np.stack([o[k] for o in obs])) for k in space.spaces.keys()])
+        assert isinstance(space.spaces, dict), "Dict space must have ordered subspaces"
+        assert isinstance(obs_list[0], dict), "non-dict observation for environment with Dict observation space"
+        return {key: np.stack([single_obs[key] for single_obs in obs_list]) for key in space.spaces.keys()}  # type: ignore[call-overload]
     elif isinstance(space, spaces.Tuple):
-        assert isinstance(obs[0], tuple), "non-tuple observation for environment with Tuple observation space"
+        assert isinstance(obs_list[0], tuple), "non-tuple observation for environment with Tuple observation space"
         obs_len = len(space.spaces)
-        return tuple(np.stack([o[i] for o in obs]) for i in range(obs_len))  # type: ignore[index]
+        return tuple(np.stack([single_obs[i] for single_obs in obs_list]) for i in range(obs_len))  # type: ignore[index]
     else:
-        return np.stack(obs)  # type: ignore[arg-type]
+        return np.stack(obs_list)  # type: ignore[arg-type]
diff --git a/stable_baselines3/common/vec_env/util.py b/stable_baselines3/common/vec_env/util.py
index 855f50edc..6ea04f6ab 100644
--- a/stable_baselines3/common/vec_env/util.py
+++ b/stable_baselines3/common/vec_env/util.py
@@ -2,7 +2,6 @@
 Helpers for dealing with vectorized environments.
 """
 
-from collections import OrderedDict
 from typing import Any, Dict, List, Tuple
 
 import numpy as np
@@ -12,17 +11,6 @@
 from stable_baselines3.common.vec_env.base_vec_env import VecEnvObs
 
 
-def copy_obs_dict(obs: Dict[str, np.ndarray]) -> Dict[str, np.ndarray]:
-    """
-    Deep-copy a dict of numpy arrays.
-
-    :param obs: a dict of numpy arrays.
-    :return: a dict of copied numpy arrays.
-    """
-    assert isinstance(obs, OrderedDict), f"unexpected type for observations '{type(obs)}'"
-    return OrderedDict([(k, np.copy(v)) for k, v in obs.items()])
-
-
 def dict_to_obs(obs_space: spaces.Space, obs_dict: Dict[Any, np.ndarray]) -> VecEnvObs:
     """
     Convert an internal representation raw_obs into the appropriate type
@@ -60,13 +48,13 @@ def obs_space_info(obs_space: spaces.Space) -> Tuple[List[str], Dict[Any, Tuple[
     """
     check_for_nested_spaces(obs_space)
     if isinstance(obs_space, spaces.Dict):
-        assert isinstance(obs_space.spaces, OrderedDict), "Dict space must have ordered subspaces"
+        assert isinstance(obs_space.spaces, dict), "Dict space must have ordered subspaces"
         subspaces = obs_space.spaces
     elif isinstance(obs_space, spaces.Tuple):
-        subspaces = {i: space for i, space in enumerate(obs_space.spaces)}  # type: ignore[assignment]
+        subspaces = {i: space for i, space in enumerate(obs_space.spaces)}  # type: ignore[assignment,misc]
     else:
         assert not hasattr(obs_space, "spaces"), f"Unsupported structured space '{type(obs_space)}'"
-        subspaces = {None: obs_space}  # type: ignore[assignment]
+        subspaces = {None: obs_space}  # type: ignore[assignment,dict-item]
     keys = []
     shapes = {}
     dtypes = {}
@@ -74,4 +62,4 @@ def obs_space_info(obs_space: spaces.Space) -> Tuple[List[str], Dict[Any, Tuple[
         keys.append(key)
         shapes[key] = box.shape
         dtypes[key] = box.dtype
-    return keys, shapes, dtypes
+    return keys, shapes, dtypes  # type: ignore[return-value]
diff --git a/stable_baselines3/common/vec_env/vec_video_recorder.py b/stable_baselines3/common/vec_env/vec_video_recorder.py
index 52faebd1f..e586f94ab 100644
--- a/stable_baselines3/common/vec_env/vec_video_recorder.py
+++ b/stable_baselines3/common/vec_env/vec_video_recorder.py
@@ -1,7 +1,9 @@
 import os
-from typing import Callable
+import os.path
+from typing import Callable, List
 
-from gymnasium.wrappers.monitoring import video_recorder
+import numpy as np
+from gymnasium import error, logger
 
 from stable_baselines3.common.vec_env.base_vec_env import VecEnv, VecEnvObs, VecEnvStepReturn, VecEnvWrapper
 from stable_baselines3.common.vec_env.dummy_vec_env import DummyVecEnv
@@ -13,6 +15,11 @@ class VecVideoRecorder(VecEnvWrapper):
     Wraps a VecEnv or VecEnvWrapper object to record rendered image as mp4 video.
     It requires ffmpeg or avconv to be installed on the machine.
 
+    Note: for now it only allows to record one video and all videos
+    must have at least two frames.
+
+    The video recorder code was adapted from Gymnasium v1.0.
+
     :param venv:
     :param video_folder: Where to save videos
     :param record_video_trigger: Function that defines when to start recording.
@@ -22,8 +29,6 @@ class VecVideoRecorder(VecEnvWrapper):
     :param name_prefix: Prefix to the video name
     """
 
-    video_recorder: video_recorder.VideoRecorder
-
     def __init__(
         self,
         venv: VecEnv,
@@ -51,6 +56,8 @@ def __init__(
         self.env.metadata = metadata
         assert self.env.render_mode == "rgb_array", f"The render_mode must be 'rgb_array', not {self.env.render_mode}"
 
+        self.frames_per_sec = self.env.metadata.get("render_fps", 30)
+
         self.record_video_trigger = record_video_trigger
         self.video_folder = os.path.abspath(video_folder)
         # Create output folder if needed
@@ -60,54 +67,88 @@ def __init__(
         self.step_id = 0
         self.video_length = video_length
 
+        self.video_name = f"{self.name_prefix}-step-{self.step_id}-to-step-{self.step_id + self.video_length}.mp4"
+        self.video_path = os.path.join(self.video_folder, self.video_name)
+
         self.recording = False
-        self.recorded_frames = 0
+        self.recorded_frames: list[np.ndarray] = []
+
+        try:
+            import moviepy  # noqa: F401
+        except ImportError as e:
+            raise error.DependencyNotInstalled("MoviePy is not installed, run `pip install 'gymnasium[other]'`") from e
 
     def reset(self) -> VecEnvObs:
         obs = self.venv.reset()
-        self.start_video_recorder()
+        if self._video_enabled():
+            self._start_video_recorder()
         return obs
 
-    def start_video_recorder(self) -> None:
-        self.close_video_recorder()
-
-        video_name = f"{self.name_prefix}-step-{self.step_id}-to-step-{self.step_id + self.video_length}"
-        base_path = os.path.join(self.video_folder, video_name)
-        self.video_recorder = video_recorder.VideoRecorder(
-            env=self.env, base_path=base_path, metadata={"step_id": self.step_id}
-        )
-
-        self.video_recorder.capture_frame()
-        self.recorded_frames = 1
-        self.recording = True
+    def _start_video_recorder(self) -> None:
+        self._start_recording()
+        self._capture_frame()
 
     def _video_enabled(self) -> bool:
         return self.record_video_trigger(self.step_id)
 
     def step_wait(self) -> VecEnvStepReturn:
-        obs, rews, dones, infos = self.venv.step_wait()
+        obs, rewards, dones, infos = self.venv.step_wait()
 
         self.step_id += 1
         if self.recording:
-            self.video_recorder.capture_frame()
-            self.recorded_frames += 1
-            if self.recorded_frames > self.video_length:
-                print(f"Saving video to {self.video_recorder.path}")
-                self.close_video_recorder()
+            self._capture_frame()
+            if len(self.recorded_frames) > self.video_length:
+                print(f"Saving video to {self.video_path}")
+                self._stop_recording()
         elif self._video_enabled():
-            self.start_video_recorder()
+            self._start_video_recorder()
 
-        return obs, rews, dones, infos
+        return obs, rewards, dones, infos
 
-    def close_video_recorder(self) -> None:
-        if self.recording:
-            self.video_recorder.close()
-        self.recording = False
-        self.recorded_frames = 1
+    def _capture_frame(self) -> None:
+        assert self.recording, "Cannot capture a frame, recording wasn't started."
+
+        frame = self.env.render()
+        if isinstance(frame, List):
+            frame = frame[-1]
+
+        if isinstance(frame, np.ndarray):
+            self.recorded_frames.append(frame)
+        else:
+            self._stop_recording()
+            logger.warn(
+                f"Recording stopped: expected type of frame returned by render to be a numpy array, got instead {type(frame)}."
+            )
 
     def close(self) -> None:
+        """Closes the wrapper then the video recorder."""
         VecEnvWrapper.close(self)
-        self.close_video_recorder()
+        if self.recording:
+            self._stop_recording()
+
+    def _start_recording(self) -> None:
+        """Start a new recording. If it is already recording, stops the current recording before starting the new one."""
+        if self.recording:
+            self._stop_recording()
+
+        self.recording = True
+
+    def _stop_recording(self) -> None:
+        """Stop current recording and saves the video."""
+        assert self.recording, "_stop_recording was called, but no recording was started"
+
+        if len(self.recorded_frames) == 0:
+            logger.warn("Ignored saving a video as there were zero frames to save.")
+        else:
+            from moviepy.video.io.ImageSequenceClip import ImageSequenceClip
+
+            clip = ImageSequenceClip(self.recorded_frames, fps=self.frames_per_sec)
+            clip.write_videofile(self.video_path)
+
+        self.recorded_frames = []
+        self.recording = False
 
-    def __del__(self):
-        self.close_video_recorder()
+    def __del__(self) -> None:
+        """Warn the user in case last video wasn't saved."""
+        if len(self.recorded_frames) > 0:
+            logger.warn("Unable to save last video! Did you call close()?")
diff --git a/stable_baselines3/version.txt b/stable_baselines3/version.txt
index 852a32b3f..d5cafdb5a 100644
--- a/stable_baselines3/version.txt
+++ b/stable_baselines3/version.txt
@@ -1 +1 @@
-2.4.0a10
+2.4.0a11
diff --git a/tests/test_dict_env.py b/tests/test_dict_env.py
index f093e47e7..8049c6887 100644
--- a/tests/test_dict_env.py
+++ b/tests/test_dict_env.py
@@ -117,12 +117,11 @@ def test_consistency(model_class):
     """
     use_discrete_actions = model_class == DQN
     dict_env = DummyDictEnv(use_discrete_actions=use_discrete_actions, vec_only=True)
+    dict_env.seed(10)
     dict_env = gym.wrappers.TimeLimit(dict_env, 100)
     env = gym.wrappers.FlattenObservation(dict_env)
-    dict_env.seed(10)
     obs, _ = dict_env.reset()
 
-    kwargs = {}
     n_steps = 256
 
     if model_class in {A2C, PPO}:
diff --git a/tests/test_gae.py b/tests/test_gae.py
index 83b95a4c0..bb674cffa 100644
--- a/tests/test_gae.py
+++ b/tests/test_gae.py
@@ -73,7 +73,7 @@ def _on_rollout_end(self):
         buffer = self.model.rollout_buffer
         rollout_size = buffer.size()
 
-        max_steps = self.training_env.envs[0].max_steps
+        max_steps = self.training_env.envs[0].get_wrapper_attr("max_steps")
         gamma = self.model.gamma
         gae_lambda = self.model.gae_lambda
         value = self.model.policy.constant_value
diff --git a/tests/test_logger.py b/tests/test_logger.py
index bc18bf2ce..02d36b306 100644
--- a/tests/test_logger.py
+++ b/tests/test_logger.py
@@ -592,6 +592,7 @@ def test_rollout_success_rate_onpolicy_algo(tmp_path):
     """
 
     STATS_WINDOW_SIZE = 10
+
     # Add dummy successes with 0.3, 0.5 and 0.8 success_rate of length STATS_WINDOW_SIZE
     dummy_successes = [
         [True] * 3 + [False] * 7,
@@ -603,16 +604,17 @@ def test_rollout_success_rate_onpolicy_algo(tmp_path):
     # Monitor the env to track the success info
     monitor_file = str(tmp_path / "monitor.csv")
     env = Monitor(DummySuccessEnv(dummy_successes, ep_steps), filename=monitor_file, info_keywords=("is_success",))
+    steps_per_log = env.unwrapped.steps_per_log
 
     # Equip the model of a custom logger to check the success_rate info
-    model = PPO("MlpPolicy", env=env, stats_window_size=STATS_WINDOW_SIZE, n_steps=env.steps_per_log, verbose=1)
+    model = PPO("MlpPolicy", env=env, stats_window_size=STATS_WINDOW_SIZE, n_steps=steps_per_log, verbose=1)
     logger = InMemoryLogger()
     model.set_logger(logger)
 
     # Make the model learn and check that the success rate corresponds to the ratio of dummy successes
-    model.learn(total_timesteps=env.ep_per_log * ep_steps, log_interval=1)
+    model.learn(total_timesteps=steps_per_log * ep_steps, log_interval=1)
     assert logger.name_to_value["rollout/success_rate"] == 0.3
-    model.learn(total_timesteps=env.ep_per_log * ep_steps, log_interval=1)
+    model.learn(total_timesteps=steps_per_log * ep_steps, log_interval=1)
     assert logger.name_to_value["rollout/success_rate"] == 0.5
-    model.learn(total_timesteps=env.ep_per_log * ep_steps, log_interval=1)
+    model.learn(total_timesteps=steps_per_log * ep_steps, log_interval=1)
     assert logger.name_to_value["rollout/success_rate"] == 0.8
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 81f134168..bb2ebd067 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,6 +1,7 @@
 import os
 import shutil
 
+import ale_py
 import gymnasium as gym
 import numpy as np
 import pytest
@@ -24,6 +25,8 @@
 )
 from stable_baselines3.common.vec_env import DummyVecEnv, SubprocVecEnv
 
+gym.register_envs(ale_py)
+
 
 @pytest.mark.parametrize("env_id", ["CartPole-v1", lambda: gym.make("CartPole-v1")])
 @pytest.mark.parametrize("n_envs", [1, 2])
diff --git a/tests/test_vec_envs.py b/tests/test_vec_envs.py
index a9516ae25..3aa52762d 100644
--- a/tests/test_vec_envs.py
+++ b/tests/test_vec_envs.py
@@ -307,7 +307,7 @@ def test_vecenv_dict_spaces(vec_env_class):
     space = spaces.Dict(SPACES)
 
     def obs_assert(obs):
-        assert isinstance(obs, collections.OrderedDict)
+        assert isinstance(obs, dict)
         assert obs.keys() == space.spaces.keys()
         for key, values in obs.items():
             check_vecenv_obs(values, space.spaces[key])