diff --git a/lib/Controller/AdminController.php b/lib/Controller/AdminController.php
index e488b5a8..d4b72cf8 100644
--- a/lib/Controller/AdminController.php
+++ b/lib/Controller/AdminController.php
@@ -133,7 +133,7 @@ class AdminController extends GenericApiController
 
             // Check for FFmpeg for preview generation
             $status['ffmpeg_preview'] = $this->getExecutableStatus(
-                Util::getSystemConfig('preview_ffmpeg_path', null, true)
+                Util::getSystemConfig('preview_ffmpeg_path')
                     ?: trim(shell_exec('which ffmpeg') ?: ''),
                 static fn ($p) => BinExt::testFFmpeg($p, 'ffmpeg'),
             );
diff --git a/lib/Service/BinExt.php b/lib/Service/BinExt.php
index 92bb3e43..502e0283 100644
--- a/lib/Service/BinExt.php
+++ b/lib/Service/BinExt.php
@@ -165,7 +165,7 @@ class BinExt
             'vaapi' => Util::getSystemConfig('memories.vod.vaapi'),
             'vaapiLowPower' => Util::getSystemConfig('memories.vod.vaapi.low_power'),
 
-            'nvenc' => Util::getSystemConfig('memories.vod.nvenc', false),
+            'nvenc' => Util::getSystemConfig('memories.vod.nvenc'),
             'nvencTemporalAQ' => Util::getSystemConfig('memories.vod.nvenc.temporal_aq'),
             'nvencScale' => Util::getSystemConfig('memories.vod.nvenc.scale'),
 
diff --git a/lib/SystemConfigDefault.php b/lib/SystemConfigDefault.php
index 27a19d3f..331854c3 100644
--- a/lib/SystemConfigDefault.php
+++ b/lib/SystemConfigDefault.php
@@ -72,4 +72,8 @@ return [
     'preview_max_y' => 4096,
     'preview_max_memory' => 128,
     'preview_max_filesize_image' => 50,
+    'preview_ffmpeg_path' => '',
+
+    // Placeholders only; these are not touched by the app
+    'instanceid' => 'default',
 ];
diff --git a/lib/Util.php b/lib/Util.php
index f4318287..bea8d079 100644
--- a/lib/Util.php
+++ b/lib/Util.php
@@ -364,17 +364,14 @@ class Util
      *
      * @param string     $key     System config key
      * @param null|mixed $default Default value
-     * @param bool       $force   Do not check if the key is valid
      */
-    public static function getSystemConfig(string $key, $default = null, bool $force = false)
+    public static function getSystemConfig(string $key, $default = null)
     {
         $config = \OC::$server->get(\OCP\IConfig::class);
 
         $defaults = self::systemConfigDefaults();
-        if (!$force) {
-            if (!\array_key_exists($key, $defaults)) {
-                throw new \InvalidArgumentException("Invalid system config key: {$key}");
-            }
+        if (!\array_key_exists($key, $defaults)) {
+            throw new \InvalidArgumentException("Invalid system config key: {$key}");
         }
 
         return $config->getSystemValue($key, $default ?? $defaults[$key]);
@@ -431,7 +428,7 @@ class Util
      */
     public static function getInstanceId(): string
     {
-        return self::getSystemConfig('instanceid', 'default', true);
+        return self::getSystemConfig('instanceid');
     }
 
     /**