links in site don’t work anymore after update WP 4.7.3

[ Moved to the Fixing WordPress sub-forum. ]

After updating tot WP 4.7.3 and updating plugins I encountered an error 500. I looked for the plugins that were updated but did not support 4.7.3. en removed these and the site is up and running again. Unfortunately in the dropdown menu the sub pages do not load automatically anymore (you need to refresh the page each time you click a submenu page in order to open that specific page. All links to pages do not work anymore. You have to click them and then refresh the page in order to be redirected to the right page.
The website is www.red-eagles.nl