diff --git a/core/lib/Drupal/Core/Config/ConfigImporter.php b/core/lib/Drupal/Core/Config/ConfigImporter.php
index e0d4e0d..26572aa 100644
--- a/core/lib/Drupal/Core/Config/ConfigImporter.php
+++ b/core/lib/Drupal/Core/Config/ConfigImporter.php
@@ -725,6 +725,13 @@ protected function validate() {
           $this->logError($this->t('Rename operation for simple configuration. Existing configuration !old_name and staged configuration !new_name.', array('old_name' => $names['old_name'], 'new_name' => $names['new_name'])));
         }
       }
+      // Ensure that modules can be uninstalled.
+      if ($reasons = $this->moduleInstaller->validateUninstall($this->getExtensionChangelist('module', 'uninstall'))) {
+        foreach ($reasons as $module => $reason) {
+          $this->logError($this->t('Unable to uninstall the %module module because: !reason.', array('%module' => $this->moduleHandler->getName($module), '!reason' => implode(', ', $reason))));
+        }
+      }
+
       $this->eventDispatcher->dispatch(ConfigEvents::IMPORT_VALIDATE, new ConfigImporterEvent($this));
       if (count($this->getErrors())) {
         throw new ConfigImporterException('There were errors validating the config synchronization.');
diff --git a/core/modules/config/src/Tests/ConfigImporterTest.php b/core/modules/config/src/Tests/ConfigImporterTest.php
index e39baf6..89c7a6c 100644
--- a/core/modules/config/src/Tests/ConfigImporterTest.php
+++ b/core/modules/config/src/Tests/ConfigImporterTest.php
@@ -649,6 +649,29 @@ public function testMissingCoreExtension() {
   }
 
   /**
+   * Tests uninstall validators being called during synchronisation.
+   *
+   * @see \Drupal\Core\EventSubscriber\ConfigImportSubscriber
+   */
+  public function testMissingExtensionValidation() {
+    $staging = $this->container->get('config.storage.staging');
+    $extensions = $staging->read('core.extension');
+    // Remove the config_test module.
+    unset($extensions['module']['system']);
+    $staging->write('core.extension', $extensions);
+
+    try {
+      $this->configImporter->reset()->import();
+      $this->fail('ConfigImporterException not thrown, invalid import was not stopped due to missing dependencies.');
+    }
+    catch (ConfigImporterException $e) {
+      $this->assertEqual($e->getMessage(), 'There were errors validating the config synchronization.');
+      $error_log = $this->configImporter->getErrors();
+      $this->assertEqual(['Unable to uninstall the <em class="placeholder">System</em> module because: The System module is required.'], $error_log);
+    }
+  }
+
+  /**
    * Tests install profile validation during configuration import.
    *
    * @see \Drupal\Core\EventSubscriber\ConfigImportSubscriber