AppArmor

If AppArmor is running, and mysql or apache2 data directories are other as the default, this must be changed in the apparmor config too.

See https://askubuntu.com/questions/916009/mysql-wont-start-because-of-apparmor

SELinux enabled

The sestatus command provides a configurable view into the status of SELinux. The simplest form of this command shows the following information:

[root@localhost ~]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /selinux
Current mode:                   enforcing
Mode from config file:          enforcing
Policy version:                 21
Policy from config file:        targeted

If SELinux is enabled, the corresponding ACL labels has to be added to the translate5 writeable files/directories.

...

Using .htaccess is not configured

If only index.php is working, but for example /login gives an 404 error, check the apache config if using .htaccess files is enabled.

In the httpd.conf there should be something like that:

<Directory "/var/www/html/public">
    Options Indexes FollowSymLinks

    AllowOverride All 

    Require all granted
</Directory>

Ensure that AllowOverride is All and not None!