If you've saved a link to the website and you're now getting a 404 Page not Found error message, check that the link is correct; the permalink may have been updated.  

If you've edited the permalink in the page, have you updated this in the menu?  See Updating the Permalink.

It might be an update that we've pushed through if it relates to one of the fixed menu items (see https://support.parish-online.co.uk/portal/en/kb/articles/menus-signposting-pages-and-pages) in which case you'll need to update the link you've saved in your favourites; just go to the top level menu and click through to the page you want and replace the link in your favourites bar with the new one.