You can experience many issues that are occurred due to less PHP memory limit. By increasing the memory limit you can fix many issues.
Below are the ways to increase the memory used by your WordPress.
You can edit your wp-config.php file and add this code before the line that says, “That’s all, stop editing! Happy publishing.”
If you have access to the php.ini file, then edit the below row and assign a large value to it.
You can also edit the .htaccess file and add the below line
php_value memory_limit 512M
In some cases, you can't set the limit, you can talk to your host to increase it.