diff --git a/core/modules/locale/locale.batch.inc b/core/modules/locale/locale.batch.inc
index ae0ea48..6dfcae6 100644
--- a/core/modules/locale/locale.batch.inc
+++ b/core/modules/locale/locale.batch.inc
@@ -238,7 +238,7 @@ function locale_translation_http_check($uri) {
       $result['location'] = $response->getEffectiveUrl();
     }
 
-    $result['last_modified'] = $response->getLastModified() ? strtotime($response->getLastModified()) : 0;
+    $result['last_modified'] = $response->hasHeader('Last-Modified') ? strtotime($response->getHeader('Last-Modified')) : 0;
     return $result;
   }
   catch (RequestException $e) {
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsAdminTest.php b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsAdminTest.php
index d6dfbab..ad68b72 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsAdminTest.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsAdminTest.php
@@ -86,16 +86,16 @@ function testStatisticsSettings() {
     $post = array('nid' => $nid);
     global $base_url;
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
 
     // Hit the node again (the counter is incremented after the hit, so
     // "1 view" will actually be shown when the node is hit the second time).
     $this->drupalGet('node/' . $this->test_node->id());
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
     $this->assertText('1 view', 'Node is viewed once.');
 
     $this->drupalGet('node/' . $this->test_node->id());
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
     $this->assertText('2 views', 'Node is viewed 2 times.');
   }
 
@@ -111,7 +111,7 @@ function testDeleteNode() {
     $post = array('nid' => $nid);
     global $base_url;
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
 
     $result = db_select('node_counter', 'n')
       ->fields('n', array('nid'))
@@ -145,9 +145,9 @@ function testExpiredLogs() {
     $post = array('nid' => $nid);
     global $base_url;
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
     $this->drupalGet('node/' . $this->test_node->id());
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
     $this->assertText('1 view', 'Node is viewed once.');
 
     // statistics_cron() will subtract
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsLoggingTest.php b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsLoggingTest.php
index a2704d8..3effaf5 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsLoggingTest.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsLoggingTest.php
@@ -93,7 +93,7 @@ function testLogging() {
     // Manually call statistics.php to simulate ajax data collection behavior.
     $nid = $this->node->id();
     $post = array('nid' => $nid);
-    $this->client->post($stats_path, array(), $post);
+    $this->client->post($stats_path, array('body' => $post));
     $node_counter = statistics_get($this->node->id());
     $this->assertIdentical($node_counter['totalcount'], '1');
   }
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsReportsTest.php b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsReportsTest.php
index fed4bdc..3d8309a 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsReportsTest.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsReportsTest.php
@@ -38,7 +38,7 @@ function testPopularContentBlock() {
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
     $client = \Drupal::httpClient();
     $client->setDefaultOption('config/curl', array(CURLOPT_TIMEOUT => 10));
-    $client->post($stats_path, $headers, $post);
+    $client->post($stats_path, array('headers' => $headers, 'body' => $post));
 
     // Configure and save the block.
     $this->drupalPlaceBlock('statistics_popular_block', array(
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTokenReplaceTest.php b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTokenReplaceTest.php
index e692173..16c1fda 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTokenReplaceTest.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTokenReplaceTest.php
@@ -42,7 +42,7 @@ function testStatisticsTokenReplacement() {
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
     $client = \Drupal::httpClient();
     $client->setDefaultOption('config/curl', array(CURLOPT_TIMEOUT => 10));
-    $client->post($stats_path, $headers, $post);
+    $client->post($stats_path, array('headers' => $headers, 'body' => $post));
     $statistics = statistics_get($node->id());
 
     // Generate and test tokens.
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/Views/IntegrationTest.php b/core/modules/statistics/lib/Drupal/statistics/Tests/Views/IntegrationTest.php
index e417f27..f7fec46 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/Views/IntegrationTest.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/Views/IntegrationTest.php
@@ -84,7 +84,7 @@ public function testNodeCounterIntegration() {
     $stats_path = $base_url . '/' . drupal_get_path('module', 'statistics'). '/statistics.php';
     $client = \Drupal::httpClient();
     $client->setDefaultOption('config/curl', array(CURLOPT_TIMEOUT => 10));
-    $client->post($stats_path, array(), array('nid' => $this->node->id()));
+    $client->post($stats_path, array('body' => array('nid' => $this->node->id())));
     $this->drupalGet('test_statistics_integration');
 
     $expected = statistics_get($this->node->id());