I apologize for the delay in responding.
This error seems to indicate that you need to increase your site’s memory available to php. Usually your hosting provider will edit your php.ini file to increase the memory_limit parameter, and they may also have to increase your web server memory limit along with any operating system limits they have. They can define this in the php.ini file (usually found in /etc on linux systems – check your documentation for windows servers, which are currently unsupported by Wordfence).
Look through the file for a line like this: memory_limit = 128M
Keep in mind the 128M is probably different. That’s the amount of memory that php is allowed to consume. If you have 10 plugins and combined they consume more memory than you have allocated, you’re going to have problems. You can assign more by increasing this value. (Some of our personal sites have 256M allowed, but these are pretty big sites with a substantial number of hits and plugins).
Our system requirements specify 128m being needed (though we use less) but were seeing many wordpress specific hosting providers allowing 256m by default to give wordpress room to breathe.
There are a few other things you can try.
1. In your wp-config.php you can try setting the amount of memory WordPress can use to a higher number. Example:
define( ‘WP_MEMORY_LIMIT’, ’96M’ );
define( ‘WP_MAX_MEMORY_LIMIT’, ‘256M’ );
2. On the Wordfence Scan > Scan Options and Scheduling in the section “Performance Options” change the setting “How much memory should Wordfence request when scanning” to 256 if it’s not already set at that.
3. Go through all your plugins and make sure you are actually using all of them. Every plugin you have activated uses a part of your available memory so the more plugins you have active the more memory your site needs.
Let me know if this helps.
Tim