diff --git a/web/setup.py b/web/setup.py
index b7234daec..5479ad210 100644
--- a/web/setup.py
+++ b/web/setup.py
@@ -496,6 +496,8 @@ class ManagePreferences:
                   sqlite_path: Optional[str] = None,
                   ):
         """Set User preferences."""
+        if not pref_options:
+            pref_options = []
 
         if input_file:
             from urllib.parse import unquote