diff --git a/static/js/app.js b/static/js/app.js
index ada9cf5..877b347 100644
--- a/static/js/app.js
+++ b/static/js/app.js
@@ -120,13 +120,14 @@ document.addEventListener('DOMContentLoaded', () => {
         if (!dbSizeBadge) return;
 
         dbSizeBadge.textContent = '용량 확인 중';
+        const targetUrl = appUrl('/api/settings/database-size');
         try {
-            const response = await fetch(appUrl('/api/settings/database-size'));
+            const response = await fetch(targetUrl);
             if (!response.ok) {
-                let errMsg = 'DB 용량 조회 실패';
+                let errMsg = `HTTP ${response.status} ${response.statusText}`;
                 try {
                     const errData = await response.json();
-                    errMsg = errData.detail || errMsg;
+                    errMsg += ` - ${errData.detail || ''}`;
                 } catch (_) {}
                 throw new Error(errMsg);
             }
@@ -136,6 +137,7 @@ document.addEventListener('DOMContentLoaded', () => {
         } catch (error) {
             dbSizeBadge.textContent = '용량 확인 실패';
             dbSizeBadge.title = error.message || 'DB 용량 조회 실패';
+            alert(`[디버그 정보]\n대상 URL: ${targetUrl}\nwindow.APP_BASE_PATH: ${window.APP_BASE_PATH}\n에러 내용: ${error.message}`);
         }
     }