diff --git a/README.md b/README.md
index 135e869b284165af0d9eebe765a90478cc7f1f31..4e7e315bc87854f056c643808796056629f27e75 100644
--- a/README.md
+++ b/README.md
@@ -35,13 +35,17 @@ _The arguments are the defaults. Therefore, they are optional._
 You can also start the **Game Server** and the **PyGame GUI** individually in different terminals.
 
 ```bash
-python3 overcooked_simulator/game_server.py --url "localhost" --port 8000
+python3 overcooked_simulator/game_server.py --url "localhost" --port 8000 --manager_ids SECRETKEY1 SECRETKEY2
 
-python3 overcooked_simulator/gui_2d_vis/overcooked_simulator.py --url "localhost" --port 8000
+python3 overcooked_simulator/gui_2d_vis/overcooked_gui.py --url "localhost" --port 8000 --manager_ids SECRETKEY1
 ```
 
 You can start also several GUIs.
 
+```bash
+python3 overcooked_simulator/gui_2d_vis/overcooked_gui.py --url "localhost" --port 8000 --manager_ids SECRETKEY2
+```
+
 You can replace the GUI with your own GUI (+ study server/matchmaking server).
 
 ### Library Installation
diff --git a/overcooked_simulator/gui_2d_vis/overcooked_gui.py b/overcooked_simulator/gui_2d_vis/overcooked_gui.py
index dd96280b2db2d3f58cf6a1daa9b29460e0d1207b..8e4e4025be52b869e3a753dc01f1eac693429041 100644
--- a/overcooked_simulator/gui_2d_vis/overcooked_gui.py
+++ b/overcooked_simulator/gui_2d_vis/overcooked_gui.py
@@ -457,6 +457,8 @@ class PyGameGUI:
             f"{self.request_url}/manage/create_env/",
             json=creation_json,
         )
+        if env_info.status_code == 403:
+            raise ValueError(f"Forbidden Request: {env_info.json()['detail']}")
         env_info = env_info.json()
         assert isinstance(env_info, dict), "Env info must be a dictionary"
         self.current_env_id = env_info["env_id"]
diff --git a/overcooked_simulator/utils.py b/overcooked_simulator/utils.py
index d99d6430b6614ecc299dbc3abe33b6be81c05e72..2d77d32145e43db8bb5c1960067453a970a39080 100644
--- a/overcooked_simulator/utils.py
+++ b/overcooked_simulator/utils.py
@@ -66,7 +66,9 @@ def url_and_port_arguments(parser):
 
 
 def disable_websocket_logging_arguments(parser):
-    parser.add_argument("--enable-websocket-logging", action="store_true", default=True)
+    parser.add_argument(
+        "--enable-websocket-logging" "", action="store_true", default=True
+    )
 
 
 def add_list_of_manager_ids_arguments(parser):
@@ -74,7 +76,7 @@ def add_list_of_manager_ids_arguments(parser):
         "-m",
         "--manager_ids",
         nargs="+",
-        type=list[str],
+        type=str,
         default=[uuid.uuid4().hex],
         help="List of manager IDs that can create environments.",
     )