diff --git a/core/lib/Drupal/Core/Config/ConfigImporter.php b/core/lib/Drupal/Core/Config/ConfigImporter.php
index ed50735..a68b587 100644
--- a/core/lib/Drupal/Core/Config/ConfigImporter.php
+++ b/core/lib/Drupal/Core/Config/ConfigImporter.php
@@ -728,7 +728,9 @@ protected function validate() {
       }
       $this->eventDispatcher->dispatch(ConfigEvents::IMPORT_VALIDATE, new ConfigImporterEvent($this));
       if (count($this->getErrors())) {
-        throw new ConfigImporterException('There were errors validating the config synchronization.');
+        $errors = $this->getErrors();
+        $errors = array_merge(['There were errors validating the config synchronization.'], $errors);
+        throw new ConfigImporterException(implode("\n", $errors));
       }
       else {
         $this->validated = TRUE;
diff --git a/core/modules/config/src/Tests/ConfigImporterTest.php b/core/modules/config/src/Tests/ConfigImporterTest.php
index c830b45..b40b84b 100644
--- a/core/modules/config/src/Tests/ConfigImporterTest.php
+++ b/core/modules/config/src/Tests/ConfigImporterTest.php
@@ -19,6 +19,16 @@
  * @group config
  */
 class ConfigImporterTest extends KernelTestBase {
+  /**
+   * The beginning of an import validation error.
+   */
+  const FAIL_MESSAGE = 'There were errors validating the config synchronization.';
+
+  /**
+   * @var string
+   *   The regular expression to match the beginning of a validation error.
+   */
+  protected $fail_regex;
 
   /**
    * Config Importer object used for testing.
@@ -35,6 +45,8 @@ class ConfigImporterTest extends KernelTestBase {
   public static $modules = array('config_test', 'system', 'config_import_test');
 
   protected function setUp() {
+    $this->fail_regex = '/^' . self::FAIL_MESSAGE . '/';
+
     parent::setUp();
 
     $this->installConfig(array('config_test'));
@@ -108,10 +120,16 @@ function testSiteUuidValidate() {
       $this->fail('ConfigImporterException not thrown, invalid import was not stopped due to mis-matching site UUID.');
     }
     catch (ConfigImporterException $e) {
-      $this->assertEqual($e->getMessage(), 'There were errors validating the config synchronization.');
-      $error_log = $this->configImporter->getErrors();
-      $expected = array('Site UUID in source storage does not match the target storage.');
-      $this->assertEqual($expected, $error_log);
+      $actual_message = $e->getMessage();
+
+      $actual_error_log = $this->configImporter->getErrors();
+      $expected_error_log = ['Site UUID in source storage does not match the target storage.'];
+      $this->assertEqual($actual_error_log, $expected_error_log);
+
+      $this->assertTrue(preg_match($this->fail_regex, $actual_message));
+      foreach ($expected_error_log as $log_row) {
+        $this->assertTrue(preg_match("/$log_row/", $actual_message));
+      }
     }
   }
 
@@ -585,7 +603,7 @@ public function testUnmetDependency() {
       $this->fail('ConfigImporterException not thrown; an invalid import was not stopped due to missing dependencies.');
     }
     catch (ConfigImporterException $e) {
-      $this->assertEqual($e->getMessage(), 'There were errors validating the config synchronization.');
+      $this->assertTrue(preg_match($this->fail_regex, $e->getMessage()));
       $error_log = $this->configImporter->getErrors();
       $expected = [
         'Unable to install the <em class="placeholder">unknown_module</em> module since it does not exist.',
@@ -616,7 +634,7 @@ public function testUnmetDependency() {
       $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.');
+      $this->assertTrue(preg_match($this->fail_regex, $e->getMessage()));
       $error_log = $this->configImporter->getErrors();
       $expected = [
         'Configuration <em class="placeholder">config_test.dynamic.dotted.config</em> depends on configuration (<em class="placeholder">unknown, unknown2</em>) that will not exist after import.',
@@ -642,7 +660,7 @@ public function testMissingCoreExtension() {
       $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.');
+      $this->assertTrue(preg_match($this->fail_regex, $e->getMessage()));
       $error_log = $this->configImporter->getErrors();
       $this->assertEqual(['The core.extension configuration does not exist.'], $error_log);
     }