diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 74be642..898ab6d 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -12,6 +12,7 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
+use Guzzle\Http\Exception\BadResponseException;
 use Guzzle\Http\Exception\RequestException;
 
 /**
@@ -52,6 +53,21 @@
 const INSTALL_TASK_RUN_IF_NOT_COMPLETED = 3;
 
 /**
+ * HTTP request result: file not found.
+ */
+const INSTALL_HTTP_NOT_FOUND = 'not found';
+
+/**
+ * HTTP request result: CURL response error. Possibly no internet connection.
+ */
+const INSTALL_HTTP_OFFLINE = 'offline';
+
+/**
+ * HTTP request result: translation file could not be downloaded.
+ */
+const INSTALL_HTTP_NOT_DOWNLOADED = 'not downloaded';
+
+/**
  * Installs Drupal either interactively or via an array of passed-in settings.
  *
  * The Drupal installation happens in a series of steps, which may be spread
@@ -1539,14 +1555,21 @@ function install_retrieve_file($uri, $destination) {
   try {
     $request = Drupal::httpClient()->get($uri, array('Accept' => 'text/plain'));
     $data = $request->send()->getBody(TRUE);
-    if (empty($data)) {
-      return FALSE;
-    }
+  }
+  catch (BadResponseException $e) {
+    // HTTP 4xx and 5xx errors.
+    return INSTALL_HTTP_NOT_FOUND;
   }
   catch (RequestException $e) {
-    return FALSE;
+    // Curl errors, no HTTP response, probably offline.
+    return INSTALL_HTTP_OFFLINE;
+  }
+  if (file_put_contents($path, $data)) {
+    return TRUE;
+  }
+  else {
+    return INSTALL_HTTP_NOT_DOWNLOADED;
   }
-  return file_put_contents($path, $data) !== FALSE;
 }
 
 /**
@@ -1564,8 +1587,13 @@ function install_check_localization_server($uri) {
     $response = $request->send();
     return TRUE;
   }
+  catch (BadResponseException $e) {
+    // HTTP 4xx and 5xx errors.
+    return INSTALL_HTTP_NOT_FOUND;
+  }
   catch (RequestException $e) {
-    return FALSE;
+    // Curl errors, no HTTP response, probably offline.
+    return INSTALL_HTTP_OFFLINE;
   }
 }
 
@@ -1961,13 +1989,23 @@ function install_check_translations($install_state) {
 
   // Check if the desirered translation file is available and if the translation
   // server can be reached, or in other words if we have an internet connection.
-  if ($translation_available = install_check_localization_server($translation_url)) {
-    $online = TRUE;
-    $server_available = TRUE;
-  }
-  else {
-    if ($server_available = install_check_localization_server($server_url)) {
-      $online = TRUE;
+  if ($translations_directory_exists && $readable && $writable) {
+    $result = install_check_localization_server($translation_url);
+    switch ($result) {
+      case ($result === TRUE):
+        $translation_available = TRUE;
+        $server_available = TRUE;
+        $online = TRUE;
+        break;
+
+      case INSTALL_HTTP_NOT_FOUND:
+        $online = TRUE;
+        $result = install_check_localization_server($server_url);
+        $server_available = $result === TRUE;
+        break;
+
+      case INSTALL_HTTP_OFFLINE:
+        break;
     }
   }
 
@@ -1988,7 +2026,7 @@ function install_check_translations($install_state) {
     // If the translations directory is not readable, throw an error.
     if (!$readable) {
       $requirements['translations directory readable'] = array(
-      'title'       => st('Translations directory'),
+        'title'       => st('Translations directory'),
         'value'       => st('The translations directory is not readable.'),
         'severity'    => REQUIREMENT_ERROR,
         'description' => st('The installer requires read permissions to %translations_directory at all times. If you are unsure how to grant file permissions, consult the <a href="@handbook_url">online handbook</a>.', array('%translations_directory' => $translations_directory, '@handbook_url' => 'http://drupal.org/server-permissions')),
@@ -1997,7 +2035,7 @@ function install_check_translations($install_state) {
     // If translations directory is not writable, throw an error.
     if (!$writable) {
       $requirements['translations directory writable'] = array(
-      'title'       => st('Translations directory'),
+        'title'       => st('Translations directory'),
         'value'       => st('The translations directory is not writable.'),
         'severity'    => REQUIREMENT_ERROR,
         'description' => st('The installer requires write permissions to %translations_directory during the installation process. If you are unsure how to grant file permissions, consult the <a href="@handbook_url">online handbook</a>.', array('%translations_directory' => $translations_directory, '@handbook_url' => 'http://drupal.org/server-permissions')),
@@ -2005,50 +2043,67 @@ function install_check_translations($install_state) {
     }
     else {
       $requirements['translations directory writable'] = array(
-      'title'       => st('Translations directory'),
+        'title'       => st('Translations directory'),
         'value'       => st('The translations directory is writable.'),
       );
     }
   }
 
-  // If the translations server can not be contacted, throw an error.
+  // If we failed to complete the http request, throw an error.
   if (!$online) {
     $requirements['online'] = array(
       'title'       => st('Internet'),
-      'value'       => st('The translation server is offline.'),
+      'value'       => st('Failed to connect.'),
       'severity'    => REQUIREMENT_ERROR,
-      'description' => st('The installer requires to contact the translation server to download a translation file. Check your internet connection and verify that your website can reach the translation server at <a href="!server_url">!server_url</a>.', array('!server_url' => $server_url)),
+      'description' => st('The installer requires to contact the translation server to download a translation file. Verify your internet connection and verify that your website can contact the translation server at <a href="!server_url">!server_url</a>.', array('!server_url' => $server_url)),
     );
   }
   else {
     $requirements['online'] = array(
       'title'       => st('Internet'),
-      'value'       => st('The translation server is online.'),
+      'value'       => st('The internet connection is working.'),
     );
-    // If translation file is not found at the translation server, throw an
-    // error.
-    if (!$translation_available) {
-      $requirements['translation available'] = array(
-      'title'       => st('Translation'),
-        'value'       => st('The %language translation is not available.', array('%language' => $language)),
+    // If the translations server can not be contacted, throw an error.
+    if (!$server_available) {
+      $requirements['server available'] = array(
+        'title'       => st('Internet'),
+        'value'       => st('Failed to contact the translation server.'),
         'severity'    => REQUIREMENT_ERROR,
-        'description' => st('The %language translation file is not available at the translation server. <a href="!url">Choose a different language</a> or select English and translate your website later.', array('%language' => $language, '!url' => check_url($_SERVER['SCRIPT_NAME']))),
+        'description' => st('The installer requires to contact the translation server to download a translation file. Verify that your website can contact the translation server at <a href="!server_url">!server_url</a>. This fault may be caused by firewall or proxy settings.', array('!server_url' => $server_url)),
       );
     }
     else {
-      $requirements['translation available'] = array(
-      'title'       => st('Translation'),
-        'value'       => st('The %language translation is available.', array('%language' => $language)),
+      $requirements['server available'] = array(
+        'title'       => st('Internet'),
+        'value'       => st('The translation server is online.'),
       );
+      // If translation file is not found at the translation server, throw an
+      // error.
+      if (!$translation_available) {
+        $requirements['translation available'] = array(
+        'title'       => st('Translation'),
+          'value'       => st('The %language translation is not available.', array('%language' => $language)),
+          'severity'    => REQUIREMENT_ERROR,
+          'description' => st('The %language translation file is not available at the translation server. <a href="!url">Choose a different language</a> or select English and translate your website later.', array('%language' => $language, '!url' => check_url($_SERVER['SCRIPT_NAME']))),
+        );
+      }
+      else {
+        $requirements['translation available'] = array(
+        'title'       => st('Translation'),
+          'value'       => st('The %language translation is available.', array('%language' => $language)),
+        );
+      }
     }
   }
 
   if ($translations_directory_exists && $readable && $writable && $translation_available) {
-    $translation_downloaded = install_retrieve_file($translation_url, $translations_directory);
+    $result = install_retrieve_file($translation_url, $translations_directory);
+
+    $translation_downloaded = $result === TRUE;
 
     if (!$translation_downloaded) {
       $requirements['translation downloaded'] = array(
-      'title'       => st('Translation'),
+        'title'       => st('Translation'),
         'value'       => st('The %language translation could not be downloaded.', array('%language' => $language)),
         'severity'    => REQUIREMENT_ERROR,
         'description' => st('The %language translation file could not be downloaded. <a href="!url">Choose a different language</a> or select English and translate your website later.', array('%language' => $language, '!url' => check_url($_SERVER['SCRIPT_NAME']))),