Enabling the WP_DEBUG function will notify you that something isn’t functioning correctly. Steps on how to enable WP_DEBUG are below:
First: Go into your directory that contains WordPress:
$ cd /usr/www/virtual/sample/www.sample.com/
Second: Now that you are in the right directory for WordPress. Please edit the PHP file called wp-config.
$ pico wp-config.php
Third: Look for the code below:
* For developers: WordPress debugging mode.
* Change this to true to enable the display of notices during development.
* It is strongly recommended that plugin and theme developers use WP_DEBUG
* in their development environments.
Fourth: Please edit the WP_DEBUG:
Finally: Save the wp-config.php