diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 4bc051d..b9df0eb 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -3045,6 +3045,12 @@ protected function assertResponse($code, $message = '', $group = 'Browser') {
   protected function assertNoResponse($code, $message = '', $group = 'Browser') {
     $curl_code = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
     $match = is_array($code) ? in_array($curl_code, $code) : $curl_code == $code;
+    $curl_download_bytes = curl_getinfo($this->curlHandle, CURLINFO_SIZE_DOWNLOAD);
+    if ($curl_download_bytes == 0) {
+      debug("Header: \n" . print_r(curl_getinfo($this->curlHandle, CURLINFO_HEADER_OUT), TRUE));
+      debug("Handle: \n" . print_r(curl_getinfo($this->curlHandle), TRUE));
+      debug("Error: \n" . print_r(curl_error($this->curlHandle), TRUE));
+    }
     return $this->assertFalse($match, $message ? $message : t('HTTP response not expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
   }
 
diff --git a/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
index d7adb65..3996210 100644
--- a/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -323,12 +323,10 @@ function simpletest_test_get_all() {
     else {
       // Select all PSR-0 classes in the Tests namespace of all modules.
       $classes = array();
-      $module_data = system_rebuild_module_data();
-      $all_data = $module_data + system_rebuild_theme_data();
-      $all_data += drupal_system_listing('/\.profile$/', 'profiles', 'name');
+      $all_data = array('system' => (object)array('uri' => 'core/modules/system/system.module'));
       foreach ($all_data as $name => $data) {
         // Build directory in which the test files would reside.
-        $tests_dir = DRUPAL_ROOT . '/' . dirname($data->uri) . '/lib/Drupal/' . $name . '/Tests';
+        $tests_dir = DRUPAL_ROOT . '/' . dirname($data->uri) . '/lib/Drupal/' . $name . '/Tests/Upgrade';
         // Scan it for test files if it exists.
         if (is_dir($tests_dir)) {
           $files = file_scan_directory($tests_dir, '/.*\.php/');
diff --git a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
index 454e3a2..9f537ef 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Upgrade/UpgradePathTestBase.php
@@ -240,7 +240,11 @@ protected function performUpgrade($register_errors = TRUE) {
     }
 
     // Go!
+    ini_set('display_errors', TRUE);
+    curl_setopt($this->curlHandle, CURLINFO_HEADER_OUT, true);
+    curl_setopt($this->curlHandle, CURLOPT_FAILONERROR, true);
     $this->drupalPost(NULL, array(), t('Apply pending updates'));
+    ini_set('display_errors', FALSE);
     if (!$this->assertResponse(200)) {
       throw new Exception('POST to update.php to apply pending updates did not return HTTP 200 status.');
     }
diff --git a/core/update.php b/core/update.php
index 46d933b..62589d4 100644
--- a/core/update.php
+++ b/core/update.php
@@ -400,7 +400,8 @@ function update_check_requirements($skip_warnings = FALSE) {
 
 // Some unavoidable errors happen because the database is not yet up-to-date.
 // Our custom error handler is not yet installed, so we just suppress them.
-ini_set('display_errors', FALSE);
+//ini_set('display_errors', FALSE);
+ini_set('display_errors', TRUE);
 
 // We prepare a minimal bootstrap for the update requirements check to avoid
 // reaching the PHP memory limit.