Pantheon release notes

The Pantheon MU Plugin v1.5.6 is now available.

WordPress sites can apply this update by applying upstream updates from the dashboard or via Terminus. WordPress (composer managed) sites can upgrade using composer update or by checking for updates in the dashboard.

Revised MU Plugin update strategy

Starting with this release, MU Plugin updates are deployed as standalone commits to the WordPress upstream, independent of WordPress core version updates. WordPress sites will now receive MU Plugin updates more frequently and as discrete, visible changes in the dashboard — rather than bundled with core version bumps.

What's new?

This release spans two MU Plugin versions, with updates concerning WordPress sites running Elasticsearch on Pantheon:

1.5.5

• Fixes an issue where wp elasticpress sync CLI commands indexed content with http:// image URLs instead of https://, causing broken images on the HTTPS frontend. A pantheon_elasticpress_force_https_in_cli filter is available for sites that need to opt out of this behavior.

1.5.6

• Fixes ElasticPress Autosuggest and Instant Results on sites using ElasticPress.io by routing browser-side search requests to the public host rather than an internal proxy URL that browsers cannot reach.

WordPress upstream

• WP_HOME and WP_SITEURL definitions in wp-config-pantheon.php are now conditional, so customer-defined values are respected and PHP notices are no longer generated when these constants are already set before wp-config-pantheon.php is included.

Solr support for WordPress and the Solr Power plugin will reach end of life on January 11, 2027. After this date, Solr-based search will no longer be available for WordPress sites on the platform.

What's changing?

Solr 3 is a legacy search technology that is being retired in favor of modern alternatives. Sites currently using Solr 3 with the Solr Power plugin will need to migrate to a supported search solution before the end-of-life date.

Recommended alternatives

Pantheon customers

We recommend migrating to Elasticsearch, now available as a Beta add-on for WordPress sites on Pantheon. Elasticsearch offers improved search relevance, real-time search-as-you-type, WooCommerce support, and more. See the Elasticsearch for WordPress Beta announcement for details.

Other options

If Elasticsearch is not the right fit for your site, consider these third-party search solutions:

• SearchWP — A WordPress-native search plugin that enhances the default WordPress search without requiring an external search service.
• Algolia Search — A hosted search API that provides fast, relevant search results with advanced features like typo tolerance and faceted filtering.

What you need to do

1. Identify any WordPress sites currently using the Solr Power plugin.
2. Choose a replacement search solution.
3. Complete your migration before January 11, 2027.

Elasticsearch is now available as a Beta add-on for WordPress sites on Pantheon. This integration is powered by ElasticPress, the leading Elasticsearch solution for WordPress.

What's included?

ElasticPress offloads search queries from your database to Elasticsearch, improving WP_Query performance and reducing load on your application server. Capabilities include:

• Full-text search — Fuzzy matching, synonyms, and weighted fields for more relevant search results.
• Instant Search — Real-time search-as-you-type results without full page reloads.
• WP_Query integration — Elasticsearch can handle WP_Query requests, reducing database load and improving page load times.
• Faceted filtering — Narrow results by category, tag, custom taxonomy, and other attributes.
• WooCommerce support — Product search and filtering for WooCommerce storefronts.
• Related content — Surface related posts and pages automatically.
• Custom content indexing — Index posts, pages, custom post types, and custom fields.

Who has access?

Elasticsearch is available to WordPress sites on Performance Small plans and above, including Elite.

How to enable it

Elasticsearch can be enabled in two ways:

• From the dashboard — Navigate to Site Settings → Add-Ons and activate Elasticsearch. Connection credentials are configured automatically.

• From Terminus — Use the search command:

Once enabled, install and activate the ElasticPress plugin in your WordPress admin and run your initial content sync. No manual credential configuration is required — EP_HOST, EP_INDEX_PREFIX, and EP_CREDENTIALS are set automatically across all environments.

Documentation

For setup instructions and additional guidance, see Elasticsearch on Pantheon.

The latest version of WordPress, 6.9.4, is available on Pantheon as of today, March 11th, 2026.

This is a security release that addresses incomplete security fixes from the previous 6.9.2 and 6.9.3 releases. Three security vulnerabilities are fixed in this version:

• A PclZip path traversal issue
• An authorization bypass on the Notes feature
• An XXE (XML External Entity) vulnerability in the external getID3 library

Action required

Upgrade to WordPress 6.9.4 right from your Pantheon dashboard or Terminus to access the latest features, fixes, and security enhancements. See related documentation for how to apply core updates.

The latest version of WordPress, 6.9.3, is available on Pantheon as of yesterday, March 10th, 2026.

This version is an immediate follow up with fixes for bugs introduced in 6.9.2, which is a security release.

Action required

Upgrade to WordPress 6.9.3 right from your Pantheon dashboard or Terminus to access the latest features, fixes, and security enhancements. See related documentation for how to apply core updates.

Pantheon has released version 2.3.1 of the WP SAML Auth WordPress plugin. This update adds a new filter for multisite environments to give developers more control over how SAML-provisioned users are added to sites. No action is required — existing behavior is unchanged.

What's new

• Multisite user provisioning control — A new wp_saml_auth_auto_add_to_blog filter allows developers to prevent auto-provisioned SAML users from being automatically added to the current site. When set to false, users are created as network-level users without a role on any specific site, giving full control over site membership. The filter defaults to true, preserving existing behavior. See #465 for details.

Update to 2.3.1 from the WordPress dashboard under Plugins > Installed Plugins, or download it from the WordPress Plugin Repository.

For more details, see the plugin changelog.

Version 1.3.5 of the Pantheon Content Publisher WordPress plugin is now available.

What's new?

• ACF integration — Sync Content Publisher metadata fields to Advanced Custom Fields. Define field mappings per post type in the plugin's Integration tab and metadata values are automatically applied on every publish.
• Custom post type support — Publish content to any public post type registered on your WordPress site. Administrators can set the target post type per collection, or select "Chosen by the author" to let document authors control it via the wp-post-type metadata field.

Update to 1.3.5 from the WordPress dashboard under Plugins > Installed Plugins, or download it from the WordPress Plugin Repository.

For more details, see the plugin changelog.

The latest version of WordPress, 6.9.1, is available on Pantheon as of February 4, 2026.

Action required

Upgrade to WordPress 6.9.1 right from your Pantheon dashboard or Terminus to access the latest features, fixes, and security enhancements. See related documentation for how to apply core updates.

Highlights

• This minor release includes fixes for 49 bugs throughout Core and the Block Editor, addressing issues affecting multiple areas of WordPress including the block editor, mail, and classic themes. For a full list of bug fixes, please refer to the release candidate announcement.

WordPress 6.9.1 is a short-cycle maintenance release. The next major version of WordPress will be 7.0; it is scheduled for release on 9 April 2026 at WordCamp Asia.

For full details about WordPress 6.9.1, see the official release announcement.