Can not create new Menu Nor can modify / customize old one.

hi , I tried modifying my old menu i couldn’t do it , the changes i made were not visible was not getting stored, i tried creating new menu but couldn’t do that either. i raised my max_input_vars to 5000 as suggested , didn’t help. can you please help me with this. i deactivated few plugins , deleted cache but still nothing happened.

1. Fatal error wheh we click widgets: Out of memory (allocated 473169920) (tried to allocate 72 bytes) in /home3/mediacti/public_html/wp-includes/post.php on line 4379

2. Fatal error:
Uncaught exception ‘Exception’ with message ‘Illegal widget setting ID: nav_menu_item[]’ in /home3/mediacti/public_html/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php:182 Stack trace: #0 /home3/mediacti/public_html/wp-includes/class-wp-customize-nav-menus.php(660): WP_Customize_Nav_Menu_Item_Setting->__construct(Object(WP_Customize_Manager), ‘nav_menu_item[]’, Array) #1 [internal function]: WP_Customize_Nav_Menus->customize_register(Object(WP_Customize_Manager)) #2 /home3/mediacti/public_html/wp-includes/class-wp-hook.php(298): call_user_func_array(Array, Array) #3 /home3/mediacti/public_html/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(”, Array) #4 /home3/mediacti/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #5 /home3/mediacti/public_html/wp-includes/class-wp-customize-manager.php(754): do_action(‘customize_regis…’, Object(WP_Customize_Manager)) #6 [internal function]: WP_Customize_Manager->wp_loaded(”) #7 /home3/mediacti/public_html/wp-includes/cla in /home3/mediacti/public_html/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php on line 182

everything is going haywire , error occourd while creating a post. :
object from empty value in /home3/mediacti/public_html/wp-admin/includes/post.php on line 641