Overview

The user clicks on the hyperlink for certain subpage and it gets him to a 404 page.

Resolution

1. Explore the site contents menu and the Pages folder.
2. Find the page that needs to be shown.
3. Click on it and find the correct URL.
4. If you cannot find the page, make sure you check too if there is a subsite with this name. (In the same Contents menu, if there is a subsite, it should be found by scrolling down to the end).
5. If you find the subsite with this name, click on it and find the correct URL.
6. With this new information, go to the Shared properties menu and edit the old link, replacing it with the new URL you just got.

Validate if the link now redirects to the proper destination.