Hi there,
in your wp-config.php file we set wp_debug to true. We also try to set WP_MEMORY_LIMIT to 64M (you have set it to 500M), but this doesn’t work. We think that you need to contact your host. Most likely, they would have to go in their php.ini file to increase or decrease the memory limit for you.
Try to check the error log file generated by the web server, if you don’t have access to that file, your hosting support can help you.
Kind regards