diff --git a/docs/misc/changelog.rst b/docs/misc/changelog.rst
index bf4e4867a..29f91cff2 100644
--- a/docs/misc/changelog.rst
+++ b/docs/misc/changelog.rst
@@ -3,7 +3,7 @@
 Changelog
 ==========
 
-Release 2.4.0a1 (WIP)
+Release 2.4.0a2 (WIP)
 --------------------------
 
 Breaking Changes:
@@ -18,6 +18,7 @@ Bug Fixes:
   and only loads the PyTorch parameters (@peteole)
 - Cast type in compute gae method to avoid error when using torch compile (@amjames)
 - `CallbackList` now sets the `.parent` attribute of child callbacks to its own `.parent`. This resolves https://github.com/DLR-RM/stable-baselines3/issues/1791 (will-maclean)
+- Fixed error when loading a model that has ``net_arch`` manually set to ``None`` (@jak3122)
 
 `SB3-Contrib`_
 ^^^^^^^^^^^^^^
@@ -1662,4 +1663,4 @@ And all the contributors:
 @anand-bala @hughperkins @sidney-tio @AlexPasqua @dominicgkerr @Akhilez @Rocamonde @tobirohrer @ZikangXiong @ReHoss
 @DavyMorgan @luizapozzobon @Bonifatius94 @theSquaredError @harveybellini @DavyMorgan @FieteO @jonasreiher @npit @WeberSamuel @troiganto
 @lutogniew @lbergmann1 @lukashass @BertrandDecoster @pseudo-rnd-thoughts @stefanbschneider @kyle-he @PatrickHelm @corentinlger
-@marekm4 @stagoverflow @rushitnshah @markscsmith @NickLucche @cschindlbeck @peteole @will-maclean
+@marekm4 @stagoverflow @rushitnshah @markscsmith @NickLucche @cschindlbeck @peteole @jak3122 @will-maclean
diff --git a/stable_baselines3/common/base_class.py b/stable_baselines3/common/base_class.py
index 4be61d65e..b2c967405 100644
--- a/stable_baselines3/common/base_class.py
+++ b/stable_baselines3/common/base_class.py
@@ -692,10 +692,9 @@ def load(  # noqa: C901
             if "device" in data["policy_kwargs"]:
                 del data["policy_kwargs"]["device"]
             # backward compatibility, convert to new format
-            if "net_arch" in data["policy_kwargs"] and len(data["policy_kwargs"]["net_arch"]) > 0:
-                saved_net_arch = data["policy_kwargs"]["net_arch"]
-                if isinstance(saved_net_arch, list) and isinstance(saved_net_arch[0], dict):
-                    data["policy_kwargs"]["net_arch"] = saved_net_arch[0]
+            saved_net_arch = data["policy_kwargs"].get("net_arch")
+            if saved_net_arch and isinstance(saved_net_arch, list) and isinstance(saved_net_arch[0], dict):
+                data["policy_kwargs"]["net_arch"] = saved_net_arch[0]
 
         if "policy_kwargs" in kwargs and kwargs["policy_kwargs"] != data["policy_kwargs"]:
             raise ValueError(
diff --git a/stable_baselines3/version.txt b/stable_baselines3/version.txt
index 48adc0106..e828d3c3d 100644
--- a/stable_baselines3/version.txt
+++ b/stable_baselines3/version.txt
@@ -1 +1 @@
-2.4.0a1
+2.4.0a2
diff --git a/tests/test_save_load.py b/tests/test_save_load.py
index 0162e3650..c7df7b26f 100644
--- a/tests/test_save_load.py
+++ b/tests/test_save_load.py
@@ -797,3 +797,15 @@ def test_cast_lr_schedule(tmp_path):
     model = PPO.load(tmp_path / "ppo.zip")
     assert type(model.lr_schedule(1.0)) is float  # noqa: E721
     assert np.allclose(model.lr_schedule(0.5), 0.5 * np.sin(1.0))
+
+
+def test_save_load_net_arch_none(tmp_path):
+    """
+    Test that the model is loaded correctly when net_arch is manually set to None.
+    See GH#1928
+    """
+    PPO("MlpPolicy", "CartPole-v1", policy_kwargs=dict(net_arch=None)).save(tmp_path / "ppo.zip")
+    model = PPO.load(tmp_path / "ppo.zip")
+    # None has been replaced by the default net arch
+    assert model.policy.net_arch is not None
+    os.remove(tmp_path / "ppo.zip")