Indications of this error could be a white screen of death, or an error message like this one: Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 2348617 bytes) in /home/username/public_html/site_folder/wp-includes/plugin.php on line xxx
Increase PHP Memory Limit in WordPress
<?php
define( 'WP_MEMORY_LIMIT', '256M' );
?>
This code tells WordPress to increase the PHP memory limit to 256MB.
http://www.wpbeginner.com/wp-tutorials/fix-wordpress-memory-exhausted-error-increase-php-memory/