Debugging Options

WordPress Debugging

Edit the site's wp-config.php file to enable WordPress debugging.

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_DISPLAY', false );
define( 'WP_DEBUG_LOG', true );

That will prevent errors from being displayed on the site and instead log them to a wp-content/debug.log file.

PHP Debugging

Via .user.ini or php.ini

display_errors = on

To log errors to a php-debug.log file use the following syntax instead.

log_errors = on
error_log = ~/php-debug.log

Via PHP Code

ini_set('display_errors','1');
ini_set('display_startup_errors','1');
error_reporting (E_ALL);