How to enable debug logging
The most common cause of a website crash is a PHP error. You can get error details in the file /wp-content/debug.log. This file contains information about all PHP issues.
Debug logging is disabled by default. Enable debug logging if there is no file /wp-content/debug.log at your site. To enable debug logging you should use FTP to open the file wp-config.php, find the line
define( 'WP_DEBUG', false ); and replace this line with a code snippet below:
define( 'WP_DEBUG', true ); define( 'WP_DEBUG_LOG', true ); define( 'WP_DEBUG_DISPLAY', false );
Add this code snippet before the line
/* That's all, stop editing! Happy blogging. */ if there is no line
define( 'WP_DEBUG', false ); in the file wp-config.php.
Related article - Debugging in WordPress.
Image - Code snippet that enables debug logging in the file wp-config.php.
Image - A place of the file /wp-content/debug.log in the files tree.