diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 42ed401c..af984400 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -99,13 +99,20 @@ Native multi agents support:
 
 [1.11.0] - 202x-yy-zz
 -----------------------
+- [FIXED] issue https://github.com/Grid2op/grid2op/issues/657
+- [FIXED] missing an import on the `MaskedEnvironment` class
 - [ADDED] possibility to set the "thermal limits" when calling `env.reset(..., options={"thermal limit": xxx})`
 - [ADDED] possibility to retrieve some structural information about elements with
   with `gridobj.get_line_info(...)`, `gridobj.get_load_info(...)`, `gridobj.get_gen_info(...)` 
   or , `gridobj.get_storage_info(...)` 
+- [ADDED] codacy badge on the readme
 - [IMPROVED] possibility to set the injections values with names
   to be consistent with other way to set the actions (*eg* set_bus)
 - [IMPROVED] error messages when creating an action which changes the injections
+- [IMPROVED] (linked to https://github.com/Grid2op/grid2op/issues/657) the way the 
+  "chronics_hander" in the ObsEnv behaves (it now fully implements the public interface of 
+  a "real" chronic_handler)
+- [IMPROVED] error message in the `FromNPY` class when the backend is checked
 
 [1.10.4] - 2024-10-15
 -------------------------
diff --git a/README.md b/README.md
index c1cddb23..32a4538b 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@
 [![PyPi_Compat](https://img.shields.io/pypi/pyversions/grid2op.svg)](https://pypi.org/project/Grid2Op/)
 [![LICENSE](https://img.shields.io/pypi/l/grid2op.svg)](https://www.mozilla.org/en-US/MPL/2.0/)
 [![Documentation Status](https://readthedocs.org/projects/grid2op/badge/?version=latest)](https://grid2op.readthedocs.io/en/latest/?badge=latest)
+[![Codacy Badge](https://app.codacy.com/project/badge/Grade/3a4e666ba20f4f20b9131e9a6081622c)](https://app.codacy.com/gh/Grid2op/grid2op/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade)
 [![CircleCI](https://dl.circleci.com/status-badge/img/gh/Grid2op/grid2op/tree/master.svg?style=svg)](https://dl.circleci.com/status-badge/redirect/gh/Grid2op/grid2op/tree/master)
 [![discord](https://discord.com/api/guilds/698080905209577513/embed.png)](https://discord.gg/cYsYrPT)
 [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/grid2op/grid2op.git/master)
diff --git a/grid2op/Chronics/_obs_fake_chronics_handler.py b/grid2op/Chronics/_obs_fake_chronics_handler.py
new file mode 100644
index 00000000..79012011
--- /dev/null
+++ b/grid2op/Chronics/_obs_fake_chronics_handler.py
@@ -0,0 +1,256 @@
+# Copyright (c) 2019-2024, RTE (https://www.rte-france.com)
+# See AUTHORS.txt
+# This Source Code Form is subject to the terms of the Mozilla Public License, version 2.0.
+# If a copy of the Mozilla Public License, version 2.0 was not distributed with this file,
+# you can obtain one at http://mozilla.org/MPL/2.0/.
+# SPDX-License-Identifier: MPL-2.0
+# This file is part of Grid2Op, Grid2Op a testbed platform to model sequential decision making in power systems.
+
+from typing import Dict, Union, Literal
+
+import grid2op
+from grid2op.Exceptions import EnvError, ChronicsError
+from grid2op.Chronics import ChangeNothing
+
+
+class _ObsCH(ChangeNothing):
+    """
+    INTERNAL
+
+    .. warning:: /!\\\\ Internal, do not use unless you know what you are doing /!\\\\
+
+    This class is reserved to internal use. Do not attempt to do anything with it.
+    """
+    
+    # properties that should not be accessed
+    @property
+    def chronicsClass(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `chronicsClass`")
+        
+    @property
+    def action_space(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `action_space`")
+    
+    @property
+    def path(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `path`")
+    
+    @property
+    def _real_data(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_real_data`")
+    
+    @property
+    def kwargs(self):
+        return {}
+
+    @kwargs.setter
+    def kwargs(self, new_value):
+        raise ChronicsError('Impossible to set the "kwargs" attribute')
+    
+    @property
+    def _kwargs(self):
+        return {}
+    
+    @property
+    def real_data(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `real_data`")
+
+    # functions overriden from the ChronicsHandler class
+    def forecasts(self):
+        return []
+    
+    def get_name(self):
+        return ""
+    
+    def next_time_step(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `next_time_step`")
+    
+    def max_episode_duration(self):
+        return 0
+    
+    def seed(self, seed):
+        """.. warning:: This function is part of the public API of ChronicsHandler but should not do anything here"""
+        pass
+    
+    def cleanup_action_space(self):
+        """.. warning:: This function is part of the public API of ChronicsHandler but should not do anything here"""
+        pass
+    
+    # methods overriden from the ChronicsHandler class (__getattr__) so forwarded to the Chronics class
+    @property
+    def gridvalueClass(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `gridvalueClass`")
+    
+    @property
+    def data(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `data`")
+    
+    @property
+    def sep(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `sep`")
+    
+    @property
+    def subpaths(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `subpaths`")
+    
+    @property
+    def _order(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_order`")
+    
+    @property
+    def chunk_size(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `chunk_size`")
+    
+    @property
+    def _order_backend_loads(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_order_backend_loads`")
+    
+    @property
+    def _order_backend_prods(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_order_backend_prods`")
+    
+    @property
+    def _order_backend_lines(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_order_backend_lines`")
+    
+    @property
+    def _order_backend_subs(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_order_backend_subs`")
+    
+    @property
+    def _names_chronics_to_backend(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_names_chronics_to_backend`")
+    
+    @property
+    def _filter(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_filter`")
+    
+    @property
+    def _prev_cache_id(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `_prev_cache_id`")
+        
+    def done(self):
+        return True
+    
+    def check_validity(self, backend):
+        return True
+    
+    def get_id(self) -> str:
+        return ""
+    
+    def shuffle(self, shuffler=None):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def sample_next_chronics(self, probabilities=None):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `sample_next_chronics`")
+    
+    def set_chunk_size(self, new_chunk_size):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def init_datetime(self):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def next_chronics(self):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def tell_id(self, id_num, previous=False):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def set_filter(self, filter_fun):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def set_chunk_size(self, new_chunk_size):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def fast_forward(self, nb_timestep):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def get_init_action(self, names_chronics_to_backend: Dict[Literal["loads", "prods", "lines"], Dict[str, str]]) -> Union["grid2op.Action.playableAction.PlayableAction", None]:
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `get_init_action`")
+        
+    def regenerate_with_new_seed(self):
+        """
+        .. warning:: 
+            This function is part of the public API of ChronicsHandler,
+            by being accessible through the __getattr__ call that is
+            forwarded to the GridValue class
+            
+            It should not do anything here.
+        """
+        pass
+    
+    def max_timestep(self):
+        raise EnvError("There are no time series in the observation from `obs.simulate`, so no `max_timestep`")
+    
\ No newline at end of file
diff --git a/grid2op/Chronics/fromNPY.py b/grid2op/Chronics/fromNPY.py
index 50d6e4c4..7ebb2ac6 100644
--- a/grid2op/Chronics/fromNPY.py
+++ b/grid2op/Chronics/fromNPY.py
@@ -232,12 +232,12 @@ def initialize(
         order_backend_subs,
         names_chronics_to_backend=None,
     ):
-        assert len(order_backend_prods) == self.n_gen
-        assert len(order_backend_loads) == self.n_load
+        assert len(order_backend_prods) == self.n_gen, f"len(order_backend_prods)={len(order_backend_prods)} vs self.n_gen={self.n_gen}"
+        assert len(order_backend_loads) == self.n_load, f"len(order_backend_loads)={len(order_backend_loads)} vs self.n_load={self.n_load}"
         if self.n_line is None:
             self.n_line = len(order_backend_lines)
         else:
-            assert len(order_backend_lines) == self.n_line
+            assert len(order_backend_lines) == self.n_line, f"len(order_backend_lines)={len(order_backend_lines)} vs self.n_line={self.n_line}"
 
         if self._forecasts is not None:
             self._forecasts.initialize(
diff --git a/grid2op/Environment/_forecast_env.py b/grid2op/Environment/_forecast_env.py
index 7378df7c..ab4d7056 100644
--- a/grid2op/Environment/_forecast_env.py
+++ b/grid2op/Environment/_forecast_env.py
@@ -7,6 +7,8 @@
 # This file is part of Grid2Op, Grid2Op a testbed platform to model sequential decision making in power systems.
 
 from typing import Tuple
+
+from grid2op.typing_variables import STEP_INFO_TYPING
 from grid2op.Action import BaseAction
 from grid2op.Observation import BaseObservation
 from grid2op.Environment.environment import Environment
@@ -23,6 +25,6 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self._do_not_erase_local_dir_cls = True
         
-    def step(self, action: BaseAction) -> Tuple[BaseObservation, float, bool, dict]:
+    def step(self, action: BaseAction) -> Tuple[BaseObservation, float, bool, STEP_INFO_TYPING]:
         self._highres_sim_counter += 1
         return super().step(action)
diff --git a/grid2op/Environment/_obsEnv.py b/grid2op/Environment/_obsEnv.py
index 29abea03..2cf21404 100644
--- a/grid2op/Environment/_obsEnv.py
+++ b/grid2op/Environment/_obsEnv.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2020, RTE (https://www.rte-france.com)
+# Copyright (c) 2019-2024, RTE (https://www.rte-france.com)
 # See AUTHORS.txt
 # This Source Code Form is subject to the terms of the Mozilla Public License, version 2.0.
 # If a copy of the Mozilla Public License, version 2.0 was not distributed with this file,
@@ -12,26 +12,15 @@
 from typing import Dict, Union, Tuple, List, Optional, Any, Literal
 
 import grid2op
-from grid2op.Exceptions.envExceptions import EnvError
 from grid2op.typing_variables import STEP_INFO_TYPING
 from grid2op.dtypes import dt_int, dt_float, dt_bool
-from grid2op.Environment.baseEnv import BaseEnv
+from grid2op.Exceptions import EnvError
 from grid2op.Chronics import ChangeNothing
+from grid2op.Chronics._obs_fake_chronics_handler import _ObsCH
 from grid2op.Rules import RulesChecker
 from grid2op.operator_attention import LinearAttentionBudget
 
-
-class _ObsCH(ChangeNothing):
-    """
-    INTERNAL
-
-    .. warning:: /!\\\\ Internal, do not use unless you know what you are doing /!\\\\
-
-    This class is reserved to internal use. Do not attempt to do anything with it.
-    """
-
-    def forecasts(self):
-        return []
+from grid2op.Environment.baseEnv import BaseEnv
 
 
 class _ObsEnv(BaseEnv):
diff --git a/grid2op/Environment/environment.py b/grid2op/Environment/environment.py
index 938a2175..a74e5ec4 100644
--- a/grid2op/Environment/environment.py
+++ b/grid2op/Environment/environment.py
@@ -2135,7 +2135,7 @@ def get_params_for_runner(self):
         else:
             msg_ = ("You are probably using a legacy backend class that cannot "
                     "be copied properly. Please upgrade your backend to the latest version.")
-            self.logger.warn(msg_)
+            self.logger.warning(msg_)
             warnings.warn(msg_)
             res["backend_kwargs"] = None
             
diff --git a/grid2op/Environment/maskedEnvironment.py b/grid2op/Environment/maskedEnvironment.py
index e3c55a7d..12bf0611 100644
--- a/grid2op/Environment/maskedEnvironment.py
+++ b/grid2op/Environment/maskedEnvironment.py
@@ -7,6 +7,7 @@
 # This file is part of Grid2Op, Grid2Op a testbed platform to model sequential decision making in power systems.
 
 import copy
+import warnings
 import numpy as np
 import os
 from typing import Tuple, Union, List
diff --git a/grid2op/tests/test_issue_657.py b/grid2op/tests/test_issue_657.py
new file mode 100644
index 00000000..4e04bb2f
--- /dev/null
+++ b/grid2op/tests/test_issue_657.py
@@ -0,0 +1,70 @@
+# Copyright (c) 2024, RTE (https://www.rte-france.com)
+# See AUTHORS.txt and https://github.com/Grid2Op/grid2op/pull/319
+# This Source Code Form is subject to the terms of the Mozilla Public License, version 2.0.
+# If a copy of the Mozilla Public License, version 2.0 was not distributed with this file,
+# you can obtain one at http://mozilla.org/MPL/2.0/.
+# SPDX-License-Identifier: MPL-2.0
+# This file is part of Grid2Op, Grid2Op a testbed platform to model sequential decision making in power systems.
+
+from logging import Logger
+import unittest
+import warnings
+
+
+from helper_path_test import PATH_DATA_TEST
+import grid2op
+from grid2op.Exceptions import ChronicsError, EnvError
+from grid2op.Action import BaseAction
+from grid2op.Environment import BaseEnv
+from grid2op.Reward import BaseReward
+
+
+class WeirdReward(BaseReward):
+    def __init__(self, logger: Logger = None):
+        super().__init__(logger)
+        
+    def __call__(self, action: BaseAction, env:BaseEnv, has_error: bool, is_done: bool, is_illegal: bool, is_ambiguous: bool) -> float:
+        return len(env.chronics_handler.get_name())
+    
+    
+class Issue657Tester(unittest.TestCase):
+    def setUp(self):
+        self.env_name = "l2rpn_case14_sandbox"
+        # create first env
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore")
+            self.env = grid2op.make("l2rpn_case14_sandbox", test=True, reward_class=WeirdReward)
+            
+    def tearDown(self) -> None:
+        self.env.close()
+        return super().tearDown()
+    
+    def test_issue_657(self):
+        obs = self.env.reset()
+        obs.simulate(self.env.action_space())
+        self.env.step(self.env.action_space())
+
+    def test_broader_names(self):
+        obs = self.env.reset()
+        obs_ch = obs._obs_env.chronics_handler
+        for attr_nm in self.env.chronics_handler.__dict__:
+            try:
+                getattr(obs_ch, attr_nm)
+            except (EnvError, ChronicsError) as exc_:
+                # access to some attributes / function might return these type of errors
+                pass 
+            except AttributeError as exc_:
+                raise TypeError(f"No know attribute {attr_nm} for obs_chronics_handler") from exc_
+            
+        for attr_nm in self.env.chronics_handler.real_data.__dict__:
+            try:
+                getattr(obs_ch, attr_nm)
+            except (EnvError, ChronicsError) as exc_:
+                # access to some attributes / function might return these type of errors
+                pass 
+            except AttributeError as exc_:
+                raise TypeError(f"No know attribute {attr_nm} (from real_data / GridValue) for obs_chronics_handler") from exc_
+            
+            
+if __name__ == "__main__":
+    unittest.main()