Unable to add more menu items in WordPress?
If you find that you can’t add additional menu items in WordPress using the WP custom menus under appearance, chances are you already have 16 items there.
It seems there is a bug which is affected by PHP’s suhosin settings with some servers – and it’s not an issue with your theme or settings inside WordPress itself.
The way to resolve it is to amend the suhosin settings in your php.ini file. If you’ve gone blank by now then you just need to contact your hosting providers support department and ask for the following to be updated:
suhosin.post.max_vars = 5000
suhosin.request.max_vars = 5000
After this update you’ll easily be able to add further menu items in WordPress – appearance – menus.
I understand that this issue is being looked into and should be resolved in future releases of Wordpress without the need to edit these server side settings.
In case you’re interested the settings allow more variables to be passed than the standard setting. The workaround in the future would be to have the menu items in an array so that this issue doesn’t arise.