wp-debug

I was always confused by tools that said to enable wp_debug logging because if I followed their instruction to turn logging on nothing happened so I just deleted them and carried on. Now it seems this is what's needed: in wp-config.php

define('WP_DEBUG', true);

define( 'WP_DEBUG_LOG', true );

define( 'WP_DEBUG_DISPLAY', false );

the instructions usually said just to do the second one, which of course did nothing cos wp_debug was still off. But turning it on means it will display error messages in the site which we don't want, hence the third line.

Amazing what you can find when you're looking for something else.