2 of 3 added 57 characters in body

First of all, enable debugging in WordPress by setting this in your wp-config.php file:

define( 'WP_DEBUG', true );

After that you could also increase the memory allocated to PHP by setting this in your wp-config.php file:

define( 'WP_MAX_MEMORY_LIMIT', '256M' );

More information about editing the wp-config.php file / WordPress configuration file, see: https://codex.wordpress.org/Editing_wp-config.php

For more information about debugging see below and/or this link: https://codex.wordpress.org/Debugging_in_WordPress

Example wp-config.php for Debugging

The following code, inserted in your wp-config.php file, will log all errors, notices, and warnings to a file called debug.log in the wp-content directory. It will also hide the errors so they do not interrupt page generation.

// Enable WP_DEBUG mode
define( 'WP_DEBUG', true );

// Enable Debug logging to the /wp-content/debug.log file
define( 'WP_DEBUG_LOG', true );

// The SAVEQUERIES definition saves the database queries to an array and that array can be displayed to help analyze those queries.  
define( 'SAVEQUERIES', true );