diff --git a/app/autoUpdater.js b/app/autoUpdater.js
index bb06b74..174baaf 100644
--- a/app/autoUpdater.js
+++ b/app/autoUpdater.js
@@ -140,6 +140,7 @@ async function downloadUpdate() {
     await autoUpdater.downloadUpdate();
   } catch (err) {
     logger.error("Download failed:", err.message);
+    throw err;
   }
 }
 
diff --git a/public/script/autoUpdate.js b/public/script/autoUpdate.js
index f8fbcad..af0b553 100644
--- a/public/script/autoUpdate.js
+++ b/public/script/autoUpdate.js
@@ -45,13 +45,31 @@ async function initUpdateUI() {
       return;
     }
 
-    btn.onclick = () => {
-      window.electronAPI.downloadUpdate();
+    const initialButtonText = btn.textContent;
+    const initialIconText = icon.textContent;
+    const initialTitleText = title.textContent;
+    const initialSubText = sub.textContent;
+
+    btn.onclick = async () => {
       btn.disabled = true;
       btn.textContent = "Downloading...";
       icon.textContent = "download";
       title.textContent = "Downloading update";
       progressWrap.style.display = "flex";
+
+      try {
+        await window.electronAPI.downloadUpdate();
+      } catch {
+        btn.disabled = false;
+        btn.textContent = initialButtonText;
+        icon.textContent = initialIconText;
+        title.textContent = initialTitleText;
+        sub.textContent = initialSubText;
+        progressWrap.style.display = "none";
+        progressFill.style.width = "0%";
+        progressPct.textContent = "0%";
+        progressEta.textContent = "";
+      }
     };
 
     window.electronAPI.onDownloadProgress((progress) => {
diff --git a/test/unit/autoUpdater.test.js b/test/unit/autoUpdater.test.js
new file mode 100644
index 0000000..cf0da48
--- /dev/null
+++ b/test/unit/autoUpdater.test.js
@@ -0,0 +1,53 @@
+const mockDownloadUpdate = jest.fn();
+const mockCheckForUpdates = jest.fn();
+const mockOn = jest.fn();
+const mockQuitAndInstall = jest.fn();
+
+jest.mock("electron-updater", () => ({
+  autoUpdater: {
+    autoDownload: true,
+    autoInstallOnAppQuit: true,
+    on: mockOn,
+    checkForUpdates: mockCheckForUpdates,
+    downloadUpdate: mockDownloadUpdate,
+    quitAndInstall: mockQuitAndInstall,
+  },
+}));
+
+jest.mock("electron", () => ({
+  app: {
+    isPackaged: true,
+  },
+}));
+
+const mockLoggerError = jest.fn();
+jest.mock("../../server/logger", () => ({
+  logger: {
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: mockLoggerError,
+  },
+}));
+
+const { downloadUpdate } = require("../../app/autoUpdater");
+
+describe("autoUpdater.downloadUpdate", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  test("resolves when electron-updater download succeeds", async () => {
+    mockDownloadUpdate.mockResolvedValue(undefined);
+
+    await expect(downloadUpdate()).resolves.toBeUndefined();
+    expect(mockDownloadUpdate).toHaveBeenCalledTimes(1);
+  });
+
+  test("rejects when electron-updater download fails", async () => {
+    const error = new Error("network down");
+    mockDownloadUpdate.mockRejectedValue(error);
+
+    await expect(downloadUpdate()).rejects.toThrow("network down");
+    expect(mockLoggerError).toHaveBeenCalledWith("Download failed:", "network down");
+  });
+});