Some servers (shared hosting plans usually) have a very low limit to PHP by default which can cause a blank screen (white screen of death) or an error on your site. Luckily increasing the memory limit to PHP is very simple and can be done with a small tweak in your wp-config.php file.
Have a look below at how to increase your memory limit or read the documentation on the WordPress CODEX.
Increasing the Memory Limit
Open your wp-config.php file via FTP and add the following code right before it says “That’s all, stop editing! Happy blogging”:
define( 'WP_MEMORY_LIMIT', '128M' );
You can alter the 128MB to the value you want, but 128MB should work pretty well for most live sites.