Why do I get a allowed/allocated memory size fatal error message?

If you get a fatal error relating to allowed or allocated memory in order to fix this you’ll have to do two things:

1) Increase default WordPress memory limit:

Using a FTP client, find the wp-config.php file, located in the root of your WordPress installation and find:

define(‘WP_DEBUG’, false);

After this add:

define(‘WP_MEMORY_LIMIT’, ‘128M’);

Some hosting environments only require this step to be made, so you can give it a try and see if the memory errors have gone. If the errors still occur continue onto step 2.

2) Increase your hosting PHP memory_limit:

You will need to access php.ini or .htaccess files which should be located in the root of your WordPress installation.

If you can't find any of this files then you will have to create them, again as in the first step, you should use a FTP client to do this.

First change the limit in the php.ini file, by adding the following:

memory_limit 64M;

If this method doesn't fix your memory errors, change the limit in the .htaccess file, by adding the following:

php_value memory_limit 64M

If you encounter any errors while trying to set the memory limit using these two methods then it means your hosting provider has locked this settings and you will have to contact them to increase this limits.