Install and verify the advanced-cache drop-in

advanced-cache.php is a WordPress core drop-in. WordPress loads that exact filename near the beginning of a request when WP_CACHE is enabled. POM Cache uses it to look for a static file before the normal plugin and theme bootstrap.

POM Cache reports the required deployment state but never edits wp-config.php and never creates, overwrites, or deletes the drop-in.

Files and constants involved

The source supplied by the plugin is:

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

The deployed WordPress filename must be:

wp-content/advanced-cache.php

The standard wp-config.php values are:

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

POM_CACHE_HOME must end with a slash and match the real POM Cache installation directory. It is needed because the drop-in runs too early to discover the plugin through WordPress’s active-plugin list.

Inspect before replacing anything

1. Open POM Cache → Advanced → WordPress configuration.
2. Read the Drop-in detected type and path.
3. If wp-content/advanced-cache.php already exists but is not recognized as POM Cache, stop.
4. Identify which plugin or hosting service owns the existing file.
5. Plan the migration or compatibility arrangement with that owner.

WordPress supports only one file at this drop-in path. Blindly overwriting another cache plugin’s file can break its runtime and leave mixed rewrite rules or stale files behind.

Deploy the POM Cache source

Use the hosting provider’s file deployment process to copy the supplied source to the WordPress drop-in path. Preserve a recoverable backup of any known previous file as part of that deployment.

Then edit wp-config.php through the normal configuration-management process and add the two constants before WordPress’s “stop editing” line. Do not define either constant twice.

If the plugin is installed somewhere other than wp-content/plugins/pom-cache/, use that absolute plugin path for POM_CACHE_HOME.

Read the status report

Refresh Advanced → WordPress configuration. The report checks:

The report also shows expected and detected values. Needs manual change is not an action button; correct the deployment source, then refresh.

Verify execution

1. Enable General → Runtime → Caching.
2. Delete the current site’s HTML cache.
3. Request a simple public page once while signed out.
4. Confirm an HTML file is generated.
5. Request the identical URL again without Apache direct rules taking precedence.
6. Inspect the response for:

X-POM-Cache: Served static cache from PHP; phase=early

That header proves the drop-in found and served the file. If Apache already handles the request, temporarily use the deployment’s safe origin/PHP verification method; do not conclude that the drop-in is broken merely because the Apache response lacks the header.

Common status problems

The drop-in is missing

Copy pom-cache-advanced-cache.php to wp-content/advanced-cache.php through deployment. Activating the plugin does not perform this copy.

The detected type belongs to another product

Do not overwrite it. Remove or migrate the previous cache system completely, including its server rules, only after confirming ownership.

WP_CACHE is false or not defined

Define it once as the boolean true, not the string "true".

POM_CACHE_HOME points to an old release path

Update it to the current installed plugin directory and retain the trailing slash.

The report is correct but no early hit occurs

Check the runtime setting, request cookies, query string, method, URL eligibility, file path, and filesystem permissions. Use Understand early cache delivery for the exact decision sequence.