People often use their web browser to test the changes that they have made during modifying plugin or theme. When there is a mistake with the code, most of the time the web browser will only display blank white screen. The problem is, sometimes the error can not be immediately visible, because the web browser in not displaying the blank white screen. However, it will be a great advantage if people can see the PHP errors instead of only seeing blank white screen.

To see the PHP errors, there is a simple constant that should be added to the wp-config.php file:

define('WP_DEBUG_DISPLAY', true);

It is not a good idea to do this on a production server, because some errors can leak important information like system paths or databases. To see the errors that occur on a production server, the reports can be put into a log file (wp-content/debug.log).

define('WP_DEBUG_LOG', true);

These methods can be done alone, or both at the same time.