Page not Found after Changing Permalinks

In WordPress, we are allow to change the URL of the pages. However, creating the custom URL may cause some problems, and here is the solution.

Change the Permalinks: using "post name" is not a bad idea, and we are able to edit the URL in the post edit page.

Page not Found may occurs for the first time we apply custom permalinks. And the solution is to enable rewrite for the apache. Reference is here. And the easiest way is:

sudo a2enmod rewrite
sudo service apache2 restart