If you see the above error message on your site, please go through this fix.
Open the wp-config.php using a code editor such as NotePad++ or Atom and add the following code just above the line that says /* That’s all, stop editing! Happy blogging. */ :
define ('WP_MEMORY_LIMIT', '300M');
For more details look at this article: https://www.000webhost.com/blog/fix-wordpress-500-internal-server-error/