diff --git a/static/js/app.js b/static/js/app.js
index 5d37711..43464dd 100644
--- a/static/js/app.js
+++ b/static/js/app.js
@@ -2148,7 +2148,15 @@ async function loadBookList() {
 
   try {
     const res = await fetch('/books/');
+    if (!res.ok) {
+      listEl.innerHTML = `<p class="muted">Server error ${res.status} loading books.</p>`;
+      return;
+    }
     const books = await res.json();
+    if (!Array.isArray(books)) {
+      listEl.innerHTML = `<p class="muted">Unexpected response from server.</p>`;
+      return;
+    }
     if (!books.length) {
       listEl.innerHTML = '<p class="muted">No books yet. Drop an .epub or .pdf above.</p>';
       return;
@@ -2169,7 +2177,7 @@ async function loadBookList() {
     }
     renderBookList(decrypted);
   } catch (e) {
-    if (listEl) listEl.innerHTML = '<p class="muted">Failed to load books.</p>';
+    if (listEl) listEl.innerHTML = `<p class="muted">Error: ${e.message}</p>`;
   }
 }