After customized permalink of the articles, the title of post remains but displays 404 page after clicking onto the title.
The reason is that apache2 does not seem to support rewrite function, so we have to turn it on manually. If the wordpress is configured by LAMP, we need to simply edit two items as follows.
a2en_mod rewrite (rewrite)
/etc/apache2/apache2.conf, find and modify:
# … other directives…