diff --git a/fastchat/serve/monitor/copilot_arena.py b/fastchat/serve/monitor/copilot_arena.py
index a5047eda1..80786e341 100644
--- a/fastchat/serve/monitor/copilot_arena.py
+++ b/fastchat/serve/monitor/copilot_arena.py
@@ -41,6 +41,9 @@ def process_copilot_arena_leaderboard(leaderboard):
 
 
 def build_copilot_arena_tab():
+    if copilot_arena_leaderboard_url is None:
+        print("Copilot Arena Leaderboard URL is not set. Skipping this leaderboard.")
+        return
     response = requests.get(copilot_arena_leaderboard_url)
     if response.status_code == 200:
         leaderboard = pd.DataFrame(response.json()["elo_data"])
diff --git a/fastchat/serve/monitor/monitor.py b/fastchat/serve/monitor/monitor.py
index 45501678c..80018a386 100644
--- a/fastchat/serve/monitor/monitor.py
+++ b/fastchat/serve/monitor/monitor.py
@@ -388,9 +388,7 @@ def highlight_rank_max(s):
             (
                 "color: green; font-weight: bold"
                 if v > 0
-                else "color: red; font-weight: bold"
-                if v < 0
-                else ""
+                else "color: red; font-weight: bold" if v < 0 else ""
             )
             for v in s
         ]
@@ -493,9 +491,9 @@ def update_leaderboard_and_plots(category, filters):
         arena_values = get_arena_table(
             arena_df,
             model_table_df,
-            arena_subset_df=arena_subset_df
-            if category != "Overall"
-            else arena_overall_sc_df,
+            arena_subset_df=(
+                arena_subset_df if category != "Overall" else arena_overall_sc_df
+            ),
             hidden_models=(
                 None
                 if len(filters) > 0 and "Show Deprecated" in filters
@@ -1052,10 +1050,15 @@ def build_leaderboard_tab(
                 build_full_leaderboard_tab(
                     elo_results_text, model_table_df, model_to_score
                 )
-            with gr.Tab("Copilot Arena Leaderboard", id=5):
-                from fastchat.serve.monitor.copilot_arena import build_copilot_arena_tab
+            try:
+                with gr.Tab("Copilot Arena Leaderboard", id=5):
+                    from fastchat.serve.monitor.copilot_arena import (
+                        build_copilot_arena_tab,
+                    )
 
-                build_copilot_arena_tab()
+                    build_copilot_arena_tab()
+            except Exception as e:
+                print(f"Unable to build Copilot Arena's Leaderboard. Error: {e}")
 
         if not show_plot:
             gr.Markdown(