If you see a "Allowed memory size exhausted" fatal error, raise your site's memory limit in wp-config.php or php.ini.
The error looks something like Fatal error: Allowed memory size of 33554432 bytes exhausted, which means PHP ran out of memory while building the page.
The easiest fix is to add these constants to wp-config.php, above the line that reads /* That's all, stop editing! Happy publishing. */:
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '256M' );
WP_MEMORY_LIMIT covers the front end, and WP_MAX_MEMORY_LIMIT covers memory-heavy admin tasks. Start at 256M; if the error persists, try 512M.
If those constants do not take effect, your host may cap memory at the PHP level. In that case edit php.ini and raise the memory_limit line (for example from 128M to 256M). If you do not have access to php.ini, your hosting provider can raise the limit for you.
After increasing the limit, review which plugins and themes are the heaviest, since a single resource-hungry plugin is often the real cause. To capture the exact error, see Turning on WordPress Debug Mode.
