Requirements and compatibility

Review this page before installing POM Cache. POM Cache supports both single-site WordPress and multisite. Its standard direct-delivery setup uses Apache and stores static files on a filesystem that PHP and the web server can both access.

Platform requirements

CloudFront is recommended in the standard POM architecture, but it is a separate edge layer. POM Cache can create origin files without CloudFront; the CDN is normally responsible for edge caching and Brotli compression.

Required WordPress constants

Add both constants to wp-config.php before WordPress loads its settings:

define( 'WP_CACHE', true );
define( 'POM_CACHE_HOME', WP_CONTENT_DIR . '/plugins/pom-cache/' );

POM_CACHE_HOME must resolve to the actual plugin directory and include the trailing slash. The Advanced → WordPress configuration section shows the expected and detected values without changing the file.

Drop-in ownership

WordPress provides one wp-content/advanced-cache.php slot for the whole installation. Before installing POM Cache, determine whether another page-cache plugin owns that file.

Do not overwrite an unfamiliar drop-in. Deactivate and migrate away from the previous cache solution according to its instructions, preserve a backup, and then install the POM Cache source file:

wp-content/plugins/pom-cache/pom-cache-advanced-cache.php

as:

wp-content/advanced-cache.php

The POM Cache Advanced tab identifies whether the deployed file matches the expected POM Cache drop-in.

Filesystem and multi-node hosting

PHP needs permission to create directories and files below the configured cache base. Apache needs permission to read them.

If several origin servers handle the same hostname, they must either share the cache storage or use an architecture that keeps generation, invalidation, and delivery consistent across nodes. POM Cache does not replicate files between servers.

Do not point the cache location at /, an ephemeral path that disappears unexpectedly, or a directory that the public web server cannot map to the supplied rules.

Single-site and multisite behavior

On a single-site installation, activation, settings, license management, and current-site cache tools belong to that site.

On multisite, network activation is the normal deployment. Cache paths distinguish the current host and, where applicable, the subsite path. Manual delete actions still operate on the current site only.

Settings saved for the current site take priority. Missing site-specific values can fall back to the main site’s effective settings. Use Fix Configuration only when you intentionally want to write those effective values for the current site.

The network/main-site license controls private updates on multisite. A subsite is not an independent POM Cache license installation.

Content compatibility

POM Cache works best when an anonymous GET request has one public representation. Review any feature that varies HTML without a recognized private cookie or URL:

• geolocation or device-specific server rendering;
• membership output shown anonymously;
• pricing that changes by visitor segment;
• A/B testing performed in PHP;
• consent systems that render materially different server HTML;
• custom carts, wishlists, or sessions outside recognized WordPress/WooCommerce cookies.

Such pages may need an explicit cache exclusion or a client-side private fragment.

WooCommerce itself is not required. When it is present, recognized WooCommerce session and cart cookies bypass static HTML delivery, but checkout and account journeys still require an end-to-end test.

Other web servers

The plugin includes Apache rules. An Nginx or another server deployment needs an equivalent configuration written and reviewed for that environment. PHP early serving can be useful during diagnosis, but it does not turn the supplied Apache integration into a verified configuration for another server.

Pre-install decision

Proceed when all of the following are true:

• the existing advanced-cache.php owner is known;
• custom permalinks are active;
• PHP can write and the web server can read the cache directory;
• the origin has a reviewed Apache or equivalent delivery plan;
• anonymous pages are suitable for shared caching;
• an administrator—or a network administrator on multisite—can manage the license and configuration;
• there is a rollback copy of wp-config.php, .htaccess, and the previous drop-in.

Then follow Install and activate POM Cache.