diff --git a/bin/update.sh b/bin/update.sh
index 71e2c630a..8bfb9d603 100755
--- a/bin/update.sh
+++ b/bin/update.sh
@@ -101,7 +101,7 @@ if ($RCI->configured) {
         if (!$error) {
           $RCI->merge_config();
           echo ". writing " . RCMAIL_CONFIG_DIR . "/config.inc.php...\n";
-          $written = file_put_contents(RCMAIL_CONFIG_DIR . '/config.inc.php', $RCI->create_config());
+          $written = $RCI->save_configfile($RCI->create_config());
         }
 
         // Success!
diff --git a/installer/config.php b/installer/config.php
index f990fc23f..fd7932af4 100644
--- a/installer/config.php
+++ b/installer/config.php
@@ -24,21 +24,35 @@ $RCI->bool_config_props = array(
 $_SESSION['allowinstaller'] = true;
 
 if (!empty($_POST['submit'])) {
-  echo '<p class="notice">Copy or download the following configuration and save it';
-  echo ' as <tt><b>config.inc.php</b></tt> within the <tt>'.RCUBE_CONFIG_DIR.'</tt> directory of your Roundcube installation.<br/>';
-  echo ' Make sure that there are no characters outside the <tt>&lt;?php ?&gt;</tt> brackets when saving the file.';
-  echo '&nbsp;<input type="button" onclick="location.href=\'index.php?_getconfig=1\'" value="Download" />';
-  if ($RCI->legacy_config) {
-      echo '<br/><br/>Afterwards, please <b>remove</b> the old configuration files <tt>main.inc.php</tt> and <tt>db.inc.php</tt>';
-      echo ' from the config directory.';
+  $_SESSION['config'] = $RCI->create_config();
+
+  if ($RCI->save_configfile($_SESSION['config'])) {
+     echo '<p class="notice">The config file was saved successfully into <tt>'.RCMAIL_CONFIG_DIR.'</tt> directory of your Roundcube installation.';
+
+     if ($RCI->legacy_config) {
+        echo '<br/><br/>Afterwards, please <b>remove</b> the old configuration files <tt>main.inc.php</tt> and <tt>db.inc.php</tt> from the config directory.';
+     }
+
+     echo '</p>';
   }
-  echo '</p>';
+  else {
+    echo '<p class="notice">Copy or download the following configuration and save it';
+    echo ' as <tt><b>config.inc.php</b></tt> within the <tt>'.RCUBE_CONFIG_DIR.'</tt> directory of your Roundcube installation.<br/>';
+    echo ' Make sure that there are no characters outside the <tt>&lt;?php ?&gt;</tt> brackets when saving the file.';
+    echo '&nbsp;<input type="button" onclick="location.href=\'index.php?_getconfig=1\'" value="Download" />';
+
+    if ($RCI->legacy_config) {
+       echo '<br/><br/>Afterwards, please <b>remove</b> the old configuration files <tt>main.inc.php</tt> and <tt>db.inc.php</tt> from the config directory.';
+    }
+
+    echo '</p>';
 
-  $textbox = new html_textarea(array('rows' => 16, 'cols' => 60, 'class' => "configfile"));
-  echo $textbox->show(($_SESSION['config'] = $RCI->create_config()));
+    $textbox = new html_textarea(array('rows' => 16, 'cols' => 60, 'class' => "configfile"));
+    echo $textbox->show(($_SESSION['config']));
+  }
 
   echo '<p class="hint">Of course there are more options to configure.
-    Have a look at the defaults.inc.php file or visit <a href="http://trac.roundcube.net/wiki/Howto_Config">Howto_Config</a> to find out.</p>';
+    Have a look at the defaults.inc.php file or visit <a href="http://trac.roundcube.net/wiki/Howto_Config" target="_blank">Howto_Config</a> to find out.</p>';
 
   echo '<p><input type="button" onclick="location.href=\'./index.php?_step=3\'" value="CONTINUE" /></p>';
 
diff --git a/installer/rcube_install.php b/installer/rcube_install.php
index 0f1bfe23e..9c9794cc2 100644
--- a/installer/rcube_install.php
+++ b/installer/rcube_install.php
@@ -34,7 +34,7 @@ class rcube_install
   var $bool_config_props = array();
 
   var $local_config = array('db_dsnw', 'default_host', 'support_url', 'des_key', 'plugins');
-  var $obsolete_config = array('db_backend', 'double_auth');
+  var $obsolete_config = array('db_backend', 'db_max_length', 'double_auth');
   var $replaced_config = array(
     'skin_path'            => 'skin',
     'locale_string'        => 'language',
@@ -44,6 +44,8 @@ class rcube_install
     'pagesize'             => 'mail_pagesize',
     'default_imap_folders' => 'default_folders',
     'top_posting'          => 'reply_mode',
+    'keep_alive'           => 'refresh_interval',
+    'min_keep_alive'       => 'min_refresh_interval',
   );
 
   // list of supported database drivers
@@ -247,7 +249,9 @@ class rcube_install
       }
 
       // skip this property
-      if ((!array_key_exists($prop, $this->defaults) || ($value == $this->defaults[$prop])) && !in_array($prop, $this->local_config)) {
+      if (($value == $this->defaults[$prop]) && !in_array($prop, $this->local_config)
+          || in_array($prop, array_merge($this->obsolete_config, array_keys($this->replaced_config)))
+          || preg_match('/^db_(table|sequence)_/', $prop)) {
         continue;
       }
 
@@ -268,6 +272,20 @@ class rcube_install
   }
 
 
+  /**
+   * save generated config file in RCUBE_CONFIG_DIR
+   *
+   * @return boolean True if the file was saved successfully, false if not
+   */
+  function save_configfile($config)
+  {
+    if (is_writable(RCUBE_CONFIG_DIR)) {
+      return file_put_contents(RCUBE_CONFIG_DIR . 'config.inc.php', $config);
+    }
+
+    return false;
+  }
+
   /**
    * Check the current configuration for missing properties
    * and deprecated or obsolete settings