diff --git a/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.info.yml b/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.info.yml
new file mode 100644
index 000000000..bc1164d95
--- /dev/null
+++ b/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.info.yml
@@ -0,0 +1,5 @@
+name: 'Disable Package Manager'
+type: module
+description: 'Disables Package Manager operations on Acquia hosting.'
+hidden: true
+core_version_requirement: ^11
diff --git a/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.services.yml b/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.services.yml
new file mode 100644
index 000000000..fac246e12
--- /dev/null
+++ b/docroot/modules/custom/acquia_disable_package_manager/acquia_disable_package_manager.services.yml
@@ -0,0 +1,5 @@
+services:
+  Drupal\acquia_disable_package_manager\AhPackageManagerDisabler:
+    tags:
+      - { name: event_subscriber }
+      - { name: config.factory.override }
diff --git a/docroot/modules/custom/acquia_disable_package_manager/composer.json b/docroot/modules/custom/acquia_disable_package_manager/composer.json
new file mode 100644
index 000000000..2c6056df1
--- /dev/null
+++ b/docroot/modules/custom/acquia_disable_package_manager/composer.json
@@ -0,0 +1,8 @@
+{
+    "name": "acquia/acquia_disable_package_manager",
+    "description": "A hidden Drupal module to disable Package Manager operations on Acquia hosting.",
+    "type": "drupal-module",
+    "require": {
+        "acquia/drupal-environment-detector": "^1.8"
+    }
+}
diff --git a/docroot/modules/custom/acquia_disable_package_manager/src/AhPackageManagerDisabler.php b/docroot/modules/custom/acquia_disable_package_manager/src/AhPackageManagerDisabler.php
new file mode 100644
index 000000000..e7c38a515
--- /dev/null
+++ b/docroot/modules/custom/acquia_disable_package_manager/src/AhPackageManagerDisabler.php
@@ -0,0 +1,94 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\acquia_disable_package_manager;
+
+use Acquia\DrupalEnvironmentDetector\AcquiaDrupalEnvironmentDetector;
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Config\ConfigFactoryOverrideInterface;
+use Drupal\Core\Config\StorageInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\package_manager\Event\PreCreateEvent;
+use Drupal\package_manager\Event\SandboxValidationEvent;
+use Drupal\package_manager\Event\StatusCheckEvent;
+use Drupal\package_manager\Validator\BaseRequirementsFulfilledValidator;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Disables Project Browser and unattended automatic updates on Acquia hosting.
+ */
+final class AhPackageManagerDisabler implements ConfigFactoryOverrideInterface, EventSubscriberInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    $events = [];
+
+    // If Package Manager is disabled, this class won't exist.
+    if (class_exists(SandboxValidationEvent::class)) {
+      $events[StatusCheckEvent::class] = $events[PreCreateEvent::class] = [
+        'disable',
+        // Run before any other validation.
+        BaseRequirementsFulfilledValidator::PRIORITY + 100,
+      ];
+    }
+    return $events;
+  }
+
+  /**
+   * Warns (or errs) because Package Manager is disabled on Acquia hosting.
+   */
+  public function disable(SandboxValidationEvent $event): void {
+    if (AcquiaDrupalEnvironmentDetector::isAhEnv()) {
+      $event->addError([
+        $this->t('Package Manager is disabled on Acquia hosting.'),
+      ]);
+      // Stop all further validation.
+      $event->stopPropagation();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function loadOverrides($names): array {
+    $overrides = [];
+
+    if (AcquiaDrupalEnvironmentDetector::isAhEnv()) {
+      if (in_array('project_browser.admin_settings', $names, TRUE)) {
+        $overrides['project_browser.admin_settings']['allow_ui_install'] = FALSE;
+      }
+      if (in_array('automatic_updates.settings', $names, TRUE)) {
+        $overrides['automatic_updates.settings']['unattended']['level'] = 'disable';
+        $overrides['automatic_updates.settings']['allow_core_minor_updates'] = FALSE;
+      }
+    }
+    return $overrides;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheSuffix(): string {
+    return 'acquia';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createConfigObject($name, $collection = StorageInterface::DEFAULT_COLLECTION): null {
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheableMetadata($name): CacheableMetadata {
+    return new CacheableMetadata();
+  }
+
+}
diff --git a/recipes/custom/acquia_trials/recipe.yml b/recipes/custom/acquia_trials/recipe.yml
index 84a7b1e1c..ddc6bb927 100644
--- a/recipes/custom/acquia_trials/recipe.yml
+++ b/recipes/custom/acquia_trials/recipe.yml
@@ -2,8 +2,9 @@ name: Acquia Trials
 type: Acquia
 description: 'Enables Acquia Trials extensions: countdown banner, getting-started checklist, and Cloud Platform promotion block.'
 install:
-  - acquia_trials_countdown
+  - acquia_disable_package_manager
   - acquia_trials_checklist
+  - acquia_trials_countdown
   - acquia_trials_cloud_platform
   - acquia_trials_id
 config: