diff --git a/docs/guide/examples.rst b/docs/guide/examples.rst
index 0d097483f..a4729bfb3 100644
--- a/docs/guide/examples.rst
+++ b/docs/guide/examples.rst
@@ -364,7 +364,7 @@ Atari Games
 
 Training a RL agent on Atari games is straightforward thanks to ``make_atari_env`` helper function.
 It will do `all the preprocessing <https://danieltakeshi.github.io/2016/11/25/frame-skipping-and-preprocessing-for-deep-q-networks-on-atari-2600-games/>`_
-and multiprocessing for you. To install the Atari environments, run the command ``pip install gym[atari, accept-rom-license]`` to install the Atari environments and ROMs, or install Stable Baselines3 with ``pip install stable-baselines3[extra]`` to install this and other optional dependencies.
+and multiprocessing for you. To install the Atari environments, run the command ``pip install gymnasium[atari,accept-rom-license]`` to install the Atari environments and ROMs, or install Stable Baselines3 with ``pip install stable-baselines3[extra]`` to install this and other optional dependencies.
 
 .. image:: ../_static/img/colab-badge.svg
    :target: https://colab.research.google.com/github/Stable-Baselines-Team/rl-colab-notebooks/blob/sb3/atari_games.ipynb
diff --git a/docs/misc/changelog.rst b/docs/misc/changelog.rst
index 25121b263..410a5df0a 100644
--- a/docs/misc/changelog.rst
+++ b/docs/misc/changelog.rst
@@ -3,10 +3,16 @@
 Changelog
 ==========
 
-Release 2.2.0a11 (WIP)
+Release 2.2.1 (2023-11-17)
 --------------------------
 **Support for options at reset, bug fixes and better error messages**
 
+.. note::
+
+  SB3 v2.2.0 was yanked after a breaking change was found in `GH#1751 <https://github.com/DLR-RM/stable-baselines3/issues/1751>`_.
+  Please use SB3 v2.2.1 and not v2.2.0.
+
+
 Breaking Changes:
 ^^^^^^^^^^^^^^^^^
 - Switched to ``ruff`` for sorting imports (isort is no longer needed), black and ruff version now require a minimum version
@@ -32,12 +38,24 @@ Bug Fixes:
 - Fixed success reward dtype in ``SimpleMultiObsEnv`` (@NixGD)
 - Fixed check_env for Sequence observation space (@corentinlger)
 - Prevents instantiating BitFlippingEnv with conflicting observation spaces (@kylesayrs)
+- Fixed ResourceWarning when loading and saving models (files were not closed), please note that only path are closed automatically,
+  the behavior stay the same for tempfiles (they need to be closed manually),
+  the behavior is now consistent when loading/saving replay buffer
 
 `SB3-Contrib`_
 ^^^^^^^^^^^^^^
+- Added ``set_options`` for ``AsyncEval``
+- Added ``rollout_buffer_class`` and ``rollout_buffer_kwargs`` arguments to TRPO
 
 `RL Zoo`_
 ^^^^^^^^^
+- Removed `gym` dependency, the package is still required for some pretrained agents.
+- Added `--eval-env-kwargs` to `train.py` (@Quentin18)
+- Added `ppo_lstm` to hyperparams_opt.py (@technocrat13)
+- Upgraded to `pybullet_envs_gymnasium>=0.4.0`
+- Removed old hacks (for instance limiting offpolicy algorithms to one env at test time)
+- Updated docker image, removed support for X server
+- Replaced deprecated `optuna.suggest_uniform(...)` by `optuna.suggest_float(..., low=..., high=...)`
 
 `SBX`_ (SB3 + Jax)
 ^^^^^^^^^^^^^^^^^^
@@ -66,11 +84,14 @@ Others:
 - Switched to PyTorch 2.1.0 in the CI (fixes type annotations)
 - Fixed ``stable_baselines3/common/policies.py`` type hints
 - Switched to ``mypy`` only for checking types
+- Added tests to check consistency when saving/loading files
 
 Documentation:
 ^^^^^^^^^^^^^^
 - Updated RL Tips and Tricks (include recommendation for evaluation, added links to DroQ, ARS and SBX).
 - Fixed various typos and grammar mistakes
+- Added PokemonRedExperiments to the project page
+- Fixed an out-of-date command for installing Atari in examples
 
 Release 2.1.0 (2023-08-17)
 --------------------------
diff --git a/docs/misc/projects.rst b/docs/misc/projects.rst
index 39803018e..2b2e2405c 100644
--- a/docs/misc/projects.rst
+++ b/docs/misc/projects.rst
@@ -229,3 +229,13 @@ intelligent agents to perform network slice placement.
 | Author: Alex Pasquali
 | Github: https://github.com/AlexPasqua/DeepNetSlice
 | Paper: **under review** (citation instructions on the project's README.md) -> see this Master's Thesis for the moment: https://etd.adm.unipi.it/theses/available/etd-01182023-110038/unrestricted/Tesi_magistrale_Pasquali_Alex.pdf
+
+
+PokemonRedExperiments
+---------------------
+
+Playing Pokemon Red with Reinforcement Learning.
+
+| Author: Peter Whidden
+| Github: https://github.com/PWhiddy/PokemonRedExperiments
+| Video: https://www.youtube.com/watch?v=DcYLT37ImBY
diff --git a/stable_baselines3/common/save_util.py b/stable_baselines3/common/save_util.py
index 332158545..0cbf6d4e2 100644
--- a/stable_baselines3/common/save_util.py
+++ b/stable_baselines3/common/save_util.py
@@ -308,14 +308,14 @@ def save_to_zip_file(
     :param pytorch_variables: Other PyTorch variables expected to contain name and value of the variable.
     :param verbose: Verbosity level: 0 for no output, 1 for info messages, 2 for debug messages
     """
-    save_path = open_path(save_path, "w", verbose=0, suffix="zip")
+    file = open_path(save_path, "w", verbose=0, suffix="zip")
     # data/params can be None, so do not
     # try to serialize them blindly
     if data is not None:
         serialized_data = data_to_json(data)
 
     # Create a zip-archive and write our objects there.
-    with zipfile.ZipFile(save_path, mode="w") as archive:
+    with zipfile.ZipFile(file, mode="w") as archive:
         # Do not try to save "None" elements
         if data is not None:
             archive.writestr("data", serialized_data)
@@ -331,6 +331,9 @@ def save_to_zip_file(
         # Save system info about the current python env
         archive.writestr("system_info.txt", get_system_info(print_info=False)[1])
 
+    if isinstance(save_path, (str, pathlib.Path)):
+        file.close()
+
 
 def save_to_pkl(path: Union[str, pathlib.Path, io.BufferedIOBase], obj: Any, verbose: int = 0) -> None:
     """
@@ -344,10 +347,12 @@ def save_to_pkl(path: Union[str, pathlib.Path, io.BufferedIOBase], obj: Any, ver
     :param obj: The object to save.
     :param verbose: Verbosity level: 0 for no output, 1 for info messages, 2 for debug messages
     """
-    with open_path(path, "w", verbose=verbose, suffix="pkl") as file_handler:
-        # Use protocol>=4 to support saving replay buffers >= 4Gb
-        # See https://docs.python.org/3/library/pickle.html
-        pickle.dump(obj, file_handler, protocol=pickle.HIGHEST_PROTOCOL)
+    file = open_path(path, "w", verbose=verbose, suffix="pkl")
+    # Use protocol>=4 to support saving replay buffers >= 4Gb
+    # See https://docs.python.org/3/library/pickle.html
+    pickle.dump(obj, file, protocol=pickle.HIGHEST_PROTOCOL)
+    if isinstance(path, (str, pathlib.Path)):
+        file.close()
 
 
 def load_from_pkl(path: Union[str, pathlib.Path, io.BufferedIOBase], verbose: int = 0) -> Any:
@@ -360,8 +365,11 @@ def load_from_pkl(path: Union[str, pathlib.Path, io.BufferedIOBase], verbose: in
         path actually exists. If path is a io.BufferedIOBase the path exists.
     :param verbose: Verbosity level: 0 for no output, 1 for info messages, 2 for debug messages
     """
-    with open_path(path, "r", verbose=verbose, suffix="pkl") as file_handler:
-        return pickle.load(file_handler)
+    file = open_path(path, "r", verbose=verbose, suffix="pkl")
+    obj = pickle.load(file)
+    if isinstance(path, (str, pathlib.Path)):
+        file.close()
+    return obj
 
 
 def load_from_zip_file(
@@ -391,14 +399,14 @@ def load_from_zip_file(
     :return: Class parameters, model state_dicts (aka "params", dict of state_dict)
         and dict of pytorch variables
     """
-    load_path = open_path(load_path, "r", verbose=verbose, suffix="zip")
+    file = open_path(load_path, "r", verbose=verbose, suffix="zip")
 
     # set device to cpu if cuda is not available
     device = get_device(device=device)
 
     # Open the zip archive and load data
     try:
-        with zipfile.ZipFile(load_path) as archive:
+        with zipfile.ZipFile(file) as archive:
             namelist = archive.namelist()
             # If data or parameters is not in the
             # zip archive, assume they were stored
@@ -450,4 +458,7 @@ def load_from_zip_file(
     except zipfile.BadZipFile as e:
         # load_path wasn't a zip file
         raise ValueError(f"Error: the file {load_path} wasn't a zip-file") from e
+    finally:
+        if isinstance(load_path, (str, pathlib.Path)):
+            file.close()
     return data, params, pytorch_variables
diff --git a/stable_baselines3/common/vec_env/subproc_vec_env.py b/stable_baselines3/common/vec_env/subproc_vec_env.py
index 83758841b..c598c735a 100644
--- a/stable_baselines3/common/vec_env/subproc_vec_env.py
+++ b/stable_baselines3/common/vec_env/subproc_vec_env.py
@@ -128,14 +128,14 @@ def step_async(self, actions: np.ndarray) -> None:
     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)
-        return _flatten_obs(obs, self.observation_space), np.stack(rews), np.stack(dones), infos
+        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]
 
     def reset(self) -> VecEnvObs:
         for env_idx, remote in enumerate(self.remotes):
             remote.send(("reset", (self._seeds[env_idx], self._options[env_idx])))
         results = [remote.recv() for remote in self.remotes]
-        obs, self.reset_infos = zip(*results)
+        obs, self.reset_infos = zip(*results)  # type: ignore[assignment]
         # Seeds and options are only used once
         self._reset_seeds()
         self._reset_options()
diff --git a/stable_baselines3/version.txt b/stable_baselines3/version.txt
index 13ce6d730..c043eea77 100644
--- a/stable_baselines3/version.txt
+++ b/stable_baselines3/version.txt
@@ -1 +1 @@
-2.2.0a11
+2.2.1
diff --git a/tests/test_save_load.py b/tests/test_save_load.py
index b574d7456..e7123e984 100644
--- a/tests/test_save_load.py
+++ b/tests/test_save_load.py
@@ -3,6 +3,7 @@
 import json
 import os
 import pathlib
+import tempfile
 import warnings
 import zipfile
 from collections import OrderedDict
@@ -747,3 +748,38 @@ def test_dqn_target_update_interval(tmp_path):
     model = DQN.load(tmp_path / "dqn_cartpole")
     os.remove(tmp_path / "dqn_cartpole.zip")
     assert model.target_update_interval == 100
+
+
+# Turn warnings into errors
+@pytest.mark.filterwarnings("error")
+def test_no_resource_warning(tmp_path):
+    # Check behavior of save/load
+    # see https://github.com/DLR-RM/stable-baselines3/issues/1751
+
+    # check that files are properly closed
+    # Create a PPO agent and save it
+    PPO("MlpPolicy", "CartPole-v1").save(tmp_path / "dqn_cartpole")
+    PPO.load(tmp_path / "dqn_cartpole")
+
+    PPO("MlpPolicy", "CartPole-v1").save(str(tmp_path / "dqn_cartpole"))
+    PPO.load(str(tmp_path / "dqn_cartpole"))
+
+    # Do the same but in memory, should not close the file
+    with tempfile.TemporaryFile() as fp:
+        PPO("MlpPolicy", "CartPole-v1").save(fp)
+        PPO.load(fp)
+        assert not fp.closed
+
+    # Same but with replay buffer
+    model = SAC("MlpPolicy", "Pendulum-v1", buffer_size=200)
+    model.save_replay_buffer(tmp_path / "replay")
+    model.load_replay_buffer(tmp_path / "replay")
+
+    model.save_replay_buffer(str(tmp_path / "replay"))
+    model.load_replay_buffer(str(tmp_path / "replay"))
+
+    with tempfile.TemporaryFile() as fp:
+        model.save_replay_buffer(fp)
+        fp.seek(0)
+        model.load_replay_buffer(fp)
+        assert not fp.closed