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To protect your site against bad bots, Blackhole needs to check each request. It does this using the WordPress init hook. When running a plugin that caches pages, the init hook may not be executed. So depending on the cache plugin, Blackhole may be unable to check the request. This post provides updated information regarding which caching plugins work best with Blackhole (free and pro version).

Note: The information in this post applies to both free and pro versions of Blackhole! Also applies to Banhammer (free and pro)!

Types of cache plugins

There are many types of cache plugins. They provide all sorts of different caching mechanisms and features. All caching features work great with Blackhole except for “page caching”. With page caching, the required init hook may not be fired, which means that plugins like Blackhole for Bad Bots are not able to check the request to see if it should be blocked. Fortunately, two of the most popular caching plugins provide settings that enable full compatibility with Blackhole.

Compatible Cache Plugins

Here is a list of the cache plugins that work great with Blackhole for Bad Bots and Blackhole Pro. If any plugin has specific requirements, they will be listed. The following plugins are fully compatible with both free and pro versions of Blackhole.

WP Super Cache

  • Required setting: Advanced tab > “Late init”
  • Also empty/clear the cache before going live

W3 Total Cache

  • Required setting: General > “Disk: Basic”
  • Required setting: Page Cache > “Late initialization”
  • Empty/reset the cache before going live

WP Fastest Cache

  • Required setting: General > “Disk: Basic”
  • Required setting: Page Cache > “Late initialization”
  • Empty/reset the cache before going live

Notes about WP Fastest Cache:

  • Banhammer (free and pro) are not yet compatible with this cache plugin
  • Blackhole (free and pro) require the free Blackhole Cache Helper

WP Rocket

  • Required to disable page caching
  • Empty/reset the cache before going live

Note: there is a submitted request for WP Rocket to add a “Late Init” feature. WP Rocket users please up-vote to help get this implemented, thank you.

SG Siteground SuperCacher

  • Disable Page Cache feature
  • Empty/reset the cache before going live

WP LiteSpeed Cache

Unverified at this point, but reports are telling us that Blackhole and WP LiteSpeed Cache work great together.

Other Cache Plugins

We haven’t tested every WordPress caching plugin, so there may be others that also are fully compatible with Blackhole. If you know of any that may work, please contact us so we can test thoroughly and then add them to the list :)

Incompatible Cache Plugins

At the time of this writing, the following cache plugins are not compatible with Blackhole (both free and pro versions). This may change in the future, as developers add more features (like the “late init” option). But for now the following plugins lack the required functionality.

  • Cache Enabler
  • Comet Cache
  • Simple Cache
  • Hyper Cache

If you know of any new features for these plugins that may enable compatibility with Blackhole, or if you know how to use existing features to enable compatibility, please contact us. Thank you!

Blackhole Cache Helper

The Cache Helper is a very simple and free plugin that enables Blackhole (both free and pro versions) to work properly with certain caching plugins (e.g., WP Fastest Cache).

Installation and Usage:

  1. Download the Cache Helper
  2. Unzip and upload to /wp-content/mu-plugins/ directory
  3. Done!

Once installed, the Cache Helper will enable Blackhole to work with plugins like WP Fastest Cache. How does it work? Blackhole link uses dynamic nonce parameter in the hidden trigger link. So if/when all site pages are cached, the trigger link won’t work, because the nonce value will not be current. The Cache Helper plugin fixes this for some caching plugins.

Testing & Troubleshooting

In our quest to make Blackhole fully compatible with all caching plugins, proxies, load balancers, and so forth, here are some things to try when testing and troubleshooting.

  • Add the blackhole trigger URL (available via the “Robots Rules” setting) to your caching plugin’s “ignore” or “exclude” setting. This is useful if your cache plugin is caching the Blackhole “warning” page.
  • Add the IP(s) of your caching service, proxy service, load balancer, etc. to the Blackhole setting, “Whitelisted IPs”. This is useful if you are using a third-party service to help with caching.

Also check out the whitelist tutorials for more information.

Remember to always test new plugins and services thoroughly. For more information on testing and troubleshooting, refer to the “Testing” section in the Blackhole Pro readme.txt.

Please report any issues or findings via the contact form. Thank you!