Pantheon release notes

PHP versions 8.4.20 and 8.5.5 are now available on the platform. These updates include bug fixes and enhancements that improve performance and stability. Updates will be applied automatically over the next few days, so no manual action is required.

Sites with Multizone Failover enabled are now eligible for the Global CDN (GCDN) Beta. Previously, Multizone Failover sites were excluded from the Beta — that restriction has been removed.

What's changed

• Multizone Failover is no longer listed as an excluded configuration for the GCDN Beta.
• Eligible Multizone Failover sites will see the GCDN Beta banner in the Pantheon site dashboard.

No action is required. If you operate a Multizone Failover site, simply look for the GCDN Beta banner on your site dashboard and follow the guided steps when you're ready to migrate.

More information

For full details on the GCDN Beta, see the GCDN Beta documentation.

As previously announced, Tika 1.18 and 1.21 have been removed from the Pantheon platform. All sites now run Tika 3 regardless of the tika_version setting in pantheon.yml.

Action Required

• If you have not already done so, remove tika_version: 1 from your pantheon.yml before May 12, 2026.
  • Any tika_version: 1 entries will be ignored until May 12, 2026, at which point they will be rejected and prevent deployments.
• Update the used Tika 1.x path to Tika 3, for details see related documentation.
  • Existing Tika 1.x file paths will continue to symlink to the new Tika 3 location for the time being, but these symlinks will be removed at a later date.

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.

As noted in our June 2025 release note, Drush 5 and 7 are no longer available on Pantheon, and pantheon.yml files retaining these retired values would eventually cause a git push to be rejected. That enforcement is now in effect.

Pantheon now rejects git push when drush_version is set to 5 or 7 in pantheon.yml. The supported values are 8, 9, and 10.

Validation runs whenever pantheon.yml changes are detected on push, including reverts. Sites with drush_version: 5 or 7 already committed are unaffected until the file is modified. A git revert or git reset that touches pantheon.yml will also trigger validation and be rejected if the retired values are present.

Action required

Customers with sites configured for Drush 5 or 7 should upgrade the Drush version in pantheon.yml to at least Drush 8:

Sites created with custom upstreams using these versions may also encounter errors on site creation or upstream updates if drush_version is still set to 5 or 7.

Pantheon Search now supports Apache Solr 9.10.0 as a Beta for Drupal 10 and 11 sites. This is available through search_api_pantheon version 8.5.0-beta1, which supports both Solr 8 and Solr 9.

What's new?

• Added Solr 9 support.
• Solr 9 brings improved security defaults, the unified highlighter, and other enhancements. See the major changes in Solr 9 for details.
• Bumped Search API Solr version requirement to 4.3.x.

Getting started with Solr 9 (Beta)

Upgrading from Solr 8 to Solr 9

1. Update the module:

   Commit and deploy the changes to your Pantheon environment.

2. Update your pantheon.yml:

   Commit and deploy the changes to your Pantheon environment.

3. Clear the cache:

4. Post the schema for the new Solr version:

5. Clear the index and reindex content:

6. Test search functionality thoroughly and report any issues in the drupal.org issue queue.

New installations

To try the Beta with Solr 9 on a new site, set the Solr version in your pantheon.yml and install the module:

For detailed setup steps, see the documentation.

What about Solr 8?

Solr 8 (8.11.4) remains fully supported. Existing Solr 8 sites can update to Search API Pantheon 8.5.x without any configuration changes.

Older Drupal versions

Pantheon Search is no longer supported for Drupal 8-9.3 as of December 2, 2025.

Solr 3 is no longer supported by Drupal 9.4+ as of December 9, 2025. Those sites must use Solr 8 or above.

Feedback and documentation

Bug reports, feature requests, and feedback should be posted in the drupal.org issue queue. For detailed installation and upgrade instructions,Pantheon Search documentation.

Starting today, all Test and Live environments that have not yet been upgraded to PHP Runtime Generation 2 will be auto-upgraded over the course of this week. Opting out is no longer available.

After this week, PHP Runtime Generation 1 will no longer be available on the platform.

Action Required

If you experience any issues following the upgrade, please review the Known Changes and Requirements and contact support for assistance.

Support for creating Next.js sites is now generally available to Pantheon customers with Gold, Platinum or Diamond Workspaces. Previously, Next.js was restricted to a private beta program.

Hosting for Next.js sites can be purchased at the same plan levels and pricing as WordPress and Drupal sites. Teams running a decoupled architecture in which Next.js reads content from a CMS on Pantheon must purchase two separate plans, though decoupling may allow WordPress or Drupal to run at a smaller plan level.

Since the beginning of our private beta program last November we have added many enhancements including:

• A cache handler to coordinate persistent caching and CDN for a Next.js site, often in conjunction with a CMS data source.
• Defaulting site creation to Next.js 16.
• Setting secret environment variables at site creation.
• Streaming build & runtime logs in the Pantheon dashboard.

For more perspective on this change to general availability, see the Pantheon blog. To learn how to run Next.js on Pantheon, read our documentation.