diff -u b/composer.lock b/composer.lock
--- b/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "e4ed5776ea9cd61afba30d3deb4934b1",
+    "content-hash": "ffa355776a1fae1e88712fae77cbc517",
     "packages": [
         {
             "name": "asm89/stack-cors",
only in patch2:
unchanged:
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,8 @@
         "symfony/filesystem": "~3.4.0",
         "symfony/finder": "~3.4.0",
         "symfony/lock": "~3.4.0",
-        "symfony/browser-kit": "^3.4.0"
+        "symfony/browser-kit": "^3.4.0",
+        "symfony/dom-crawler": "^3.4.0 !=3.4.38"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
only in patch2:
unchanged:
--- a/composer/Metapackage/DevDependencies/composer.json
+++ b/composer/Metapackage/DevDependencies/composer.json
@@ -21,6 +21,7 @@
         "symfony/browser-kit": "^3.4.0",
         "symfony/css-selector": "^3.4.0",
         "symfony/debug": "^3.4.0",
+        "symfony/dom-crawler": "^3.4.0 !=3.4.38",
         "symfony/filesystem": "~3.4.0",
         "symfony/finder": "~3.4.0",
         "symfony/lock": "~3.4.0",
only in patch2:
unchanged:
--- a/core/modules/migrate/tests/src/Functional/process/DownloadFunctionalTest.php
+++ b/core/modules/migrate/tests/src/Functional/process/DownloadFunctionalTest.php
@@ -73,7 +73,7 @@ public function testExceptionThrow() {
     $messages = $id_map_plugin->getMessages(['url' => $invalid_url])->fetchAll();
     $this->assertCount(1, $messages);
     $message = reset($messages);
-    $this->assertEquals("Cannot read from non-readable stream ($invalid_url)", $message->message);
+    $this->assertEquals("Client error: `GET $invalid_url` resulted in a `404 Not Found` response ($invalid_url)", $message->message);
     $this->assertEquals(MigrationInterface::MESSAGE_ERROR, $message->level);
 
     // Check that the second row was migrated successfully.
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/UiHelperTrait.php
+++ b/core/tests/Drupal/Tests/UiHelperTrait.php
@@ -528,7 +528,7 @@ protected function checkForMetaRefresh() {
     if (!empty($refresh) && (!isset($this->maximumMetaRefreshCount) || $this->metaRefreshCount < $this->maximumMetaRefreshCount)) {
       // Parse the content attribute of the meta tag for the format:
       // "[delay]: URL=[page_to_redirect_to]".
-      if (preg_match('/\d+;\s*URL=(?<url>.*)/i', $refresh[0]->getAttribute('content'), $match)) {
+      if (preg_match('/\d+;\s*URL=\'?(?<url>[^\']*)/i', $refresh[0]->getAttribute('content'), $match)) {
         $this->metaRefreshCount++;
         return $this->drupalGet($this->getAbsoluteUrl(Html::decodeEntities($match['url'])));
       }