Reply To: Server error (500 error) and after update layout/menus problems .

Hello,

To set the menu for the mobile side menu you need to Go to Appearance >> Menus >> Edit Menu that you want to use as mobile side menu >> Scroll down and set it as mobile side menu.

Screenshot for Clarification: https://ibb.co/S52hP0p

Please read the following article for help about 500 error:
https://elementor.com/help/500-error/

Best Regards