Solved Wordpress cannot add menu item

Recently we encountered a problem wherein we cannot add anymore menu-items to our wordpress main navigation menu. On top of that the theme's menu assignment is unchecked whenever we tried to add a menu-item and hit save.

Solution:
Add the following php property to your php.ini

max_input_nesting_levels = 500
max_input_vars = 6000

Common issues:

1. max_input_vars does not take effect when you look into php properties using script.
1. Solution: if you have several domains on one hosting package, make sure that you duplicate php.ini to the root of your other domain
2. Values are already updated, phpinfo is already showing the correct values but still I can't add a menu-item.
1. Solution: copy the php.ini inside your wp-admin folder.