What is a Must-Use (MU) Plugin?

A Must-Use (MU) plugin is a specialized WordPress plugin that is considered essential for your site’s operation.

These plugins are located in a specific sub-tab within your WordPress admin:

Must-Use plugins are often installed by security services or your hosting provider.

Unlike regular plugins, they cannot be deleted or deactivated directly from the WordPress dashboard.

Generally, you should not modify these files unless you are an advanced user.

The Copilhost MU Plugin

At Copilhost, we provide a dedicated MU plugin that is vital for the proper functioning of your hosting environment.

You should never delete this plugin.

It handles the automatic purging of the following caches:

• Cloudflare
• WordPress Object Cache (wp_cache_flush)
• OPcache

How does the auto-purge work?

Our plugin monitors specific WordPress hooks to trigger a cache clear only when necessary:

• Cloudflare cache: Purged during theme changes/edits, post or attachment deletions, status changes (posts/comments), new comments, or Autoptimize purges.
• WordPress & OPcache: Purged during menu updates, term edits, or term deletions.

The goal is simple: to leverage advanced caching technologies to boost your site's speed while ensuring your visitors always see the most up-to-date content.

In short, whenever you modify a page, we clear the appropriate caches for you.

What if I accidentally deleted the Copilhost MU plugin?

Don't worry, you can reinstall it in seconds:

1. Navigate to the "Advanced" tab of your site in the Copilhost panel.
2. Scroll down to find the "Reinstall Copilhost Plugin" button.

If you are unsure whether the plugin is correctly installed, you can click this button at any time.

It is a safe action and will not break your website.

Updated on: 21/04/2026