define( 'WP_DEBUG', 1 );
define( 'WP_DEBUG_LOG', 1);
define( 'WP_DEBUG_DISPLAY', 0 );

These lines belong in wp-config.php. Usually by default you’ll have a single line that has WP_DEBUG defined as false or 0. It’s important to find that line and edit it to avoid having your debug lines overwritten.

View All