Fix prefs UI when built w/o Cycles

release/scripts/startup/bl_ui/space_userpref.py

@@ -429,8 +429,11 @@ class USERPREF_PT_system(Panel):
 
         col.separator()
 
-        if userpref.addons.find('cycles') != -1:
-            userpref.addons['cycles'].preferences.draw_impl(col, context)
+        if bpy.app.build_options.cycles:
+            addon = userpref.addons.get("cycles")
+            if addon is not None:
+                addon.preferences.draw_impl(col, context)
+            del addon
 
         if hasattr(system, "opensubdiv_compute_type"):
             col.label(text="OpenSubdiv compute:")