diff --git a/frontend/src/hooks/useAppSettings.ts b/frontend/src/hooks/useAppSettings.ts
index d26ab11..fe1736c 100644
--- a/frontend/src/hooks/useAppSettings.ts
+++ b/frontend/src/hooks/useAppSettings.ts
@@ -119,7 +119,9 @@ function ensureLoaded(): Promise<AppSettingsDto> {
     if (generation === _loadGeneration) {
       notifyAppSettingsListeners();
     }
-    return _cache;
+    // loadStrategies() 등 await 중 invalidateAppSettingsCache()가 호출되면
+    // _cache 가 null 로 초기화될 수 있으므로 ?? {} 로 null 반환 방지
+    return _cache ?? {};
   });
   return _loadPromise;
 }
@@ -234,11 +236,12 @@ export function useAppSettings(sessionKey = 0) {
     }
 
     ensureLoaded().then(data => {
+      const safe = data ?? {};
       if (mountedRef.current) {
-        setSettings(data);
-        setDisplayTimezone(normalizeTimezone(data.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE));
-        setChartTimeFormat(normalizeChartTimeFormat(data.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT));
-        setTradeAlertTimeFormat(normalizeChartTimeFormat(data.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT));
+        setSettings(safe);
+        setDisplayTimezone(normalizeTimezone(safe.displayTimezone ?? DEFAULT_DISPLAY_TIMEZONE));
+        setChartTimeFormat(normalizeChartTimeFormat(safe.chartTimeFormat ?? DEFAULT_CHART_TIME_FORMAT));
+        setTradeAlertTimeFormat(normalizeChartTimeFormat(safe.tradeAlertTimeFormat ?? DEFAULT_TRADE_ALERT_TIME_FORMAT));
         setIsLoaded(true);
       }
     }).catch(err => {