diff --git a/lib/backup-crypto.js b/lib/backup-crypto.js
index 6e18bc8..48d3a47 100644
--- a/lib/backup-crypto.js
+++ b/lib/backup-crypto.js
@@ -18,6 +18,7 @@ function deriveKey(password, salt) {
  * Returns a Buffer: MHU1 | salt(16) | iv(12) | tag(16) | ciphertext
  */
 function encrypt(config, password) {
+  if (!password || typeof password !== 'string') throw new Error('Passwort darf nicht leer sein');
   const plaintext = Buffer.from(JSON.stringify(config), 'utf-8');
   const salt = crypto.randomBytes(SALT_LEN);
   const iv = crypto.randomBytes(IV_LEN);
@@ -37,6 +38,7 @@ function encrypt(config, password) {
  * Returns the config object or throws on invalid password/data.
  */
 function decrypt(buffer, password) {
+  if (!password || typeof password !== 'string') throw new Error('Passwort darf nicht leer sein');
   if (buffer.length < MAGIC.length + SALT_LEN + IV_LEN + TAG_LEN + 1) {
     throw new Error('Ungültiges Backup-Format');
   }
diff --git a/lib/updater.js b/lib/updater.js
index a9fc8b6..1dfbd7c 100644
--- a/lib/updater.js
+++ b/lib/updater.js
@@ -152,6 +152,9 @@ async function installUpdate(onProgress) {
     if (!check || !check.available) {
       throw new Error('Kein Update verfuegbar');
     }
+    if (!check.assetUrl || !check.assetName) {
+      throw new Error('Update-Asset unvollstaendig (URL oder Name fehlt)');
+    }
 
     // Stage: downloading
     const tmpDir = app.getPath('temp');
diff --git a/tests/config-store.test.js b/tests/config-store.test.js
index 5dcf9c1..f62e24a 100644
--- a/tests/config-store.test.js
+++ b/tests/config-store.test.js
@@ -51,22 +51,24 @@ describe('ConfigStore', () => {
   });
 
   it('save then load round-trips', async () => {
-    await store.save({ hosters: { 'doodstream.com': { enabled: true, apiKey: 'test-key-123' } } });
+    await store.save({ hosters: { 'doodstream.com': [{ id: 'test-1', enabled: true, authType: 'api', apiKey: 'test-key-123' }] } });
     const config = store.load();
-    assert.equal(config.hosters['doodstream.com'].apiKey, 'test-key-123');
+    assert.equal(config.hosters['doodstream.com'][0].apiKey, 'test-key-123');
   });
 
   it('load merges with defaults for missing hosters', () => {
-    // Write partial config
+    // Write partial config in old single-object format (triggers migration)
     fs.writeFileSync(store.filePath, JSON.stringify({
       hosters: { 'doodstream.com': { apiKey: 'abc' } }
     }), 'utf-8');
 
     const config = store.load();
-    assert.equal(config.hosters['doodstream.com'].apiKey, 'abc');
-    // Other hosters should still have defaults
-    assert.equal(config.hosters['voe.sx'].enabled, true);
-    assert.equal(config.hosters['voe.sx'].apiKey, '');
+    // Old format is migrated to array
+    assert.ok(Array.isArray(config.hosters['doodstream.com']));
+    assert.equal(config.hosters['doodstream.com'][0].apiKey, 'abc');
+    // Other hosters should still have defaults (empty arrays)
+    assert.ok(Array.isArray(config.hosters['voe.sx']));
+    assert.equal(config.hosters['voe.sx'].length, 0);
   });
 
   it('hosterSettings merge fills gaps with defaults', () => {
@@ -83,11 +85,11 @@ describe('ConfigStore', () => {
   it('save only updates provided sections', async () => {
     // Save hoster settings first
     await store.save({ hosterSettings: { 'doodstream.com': { retries: 10, maxSpeedKbs: 0, parallelCount: 2, restartBelowKbs: 0, timeIntervalSec: 0, maxSizeMb: 0 } } });
-    // Save hosters credentials separately
-    await store.save({ hosters: { 'doodstream.com': { enabled: true, apiKey: 'key123' } } });
+    // Save hosters credentials separately (array format)
+    await store.save({ hosters: { 'doodstream.com': [{ id: 'test-1', enabled: true, authType: 'api', apiKey: 'key123' }] } });
 
     const config = store.load();
-    assert.equal(config.hosters['doodstream.com'].apiKey, 'key123');
+    assert.equal(config.hosters['doodstream.com'][0].apiKey, 'key123');
     assert.equal(config.hosterSettings['doodstream.com'].retries, 10); // preserved
   });