diff --git a/gulliver/methods/errors/block.css b/gulliver/methods/errors/block.css
new file mode 100644
index 000000000..5dd5a2261
--- /dev/null
+++ b/gulliver/methods/errors/block.css
@@ -0,0 +1,92 @@
+*, *:before, *:after {
+    -webkit-box-sizing: border-box;
+    -moz-box-sizing: border-box;
+    box-sizing: border-box;
+}
+
+body {
+    font-family: "Helvetica Neue", Roboto, Arial, "Droid Sans", sans-serif;
+    font-size: 13px;
+    font-weight: 400;
+    line-height: 1.471;
+}
+
+.special-page {
+    color: #fff;
+    background: #3397e2;
+}
+
+.container {
+    width: 100%;
+    padding: 0;
+}
+
+.col-md-55, .col-xs-1, .col-sm-1, .col-md-1, .col-lg-1, .col-xs-2, .col-sm-2, .col-md-2, .col-lg-2, .col-xs-3, .col-sm-3, .col-md-3, .col-lg-3, .col-xs-4, .col-sm-4, .col-md-4, .col-lg-4, .col-xs-5, .col-sm-5, .col-md-5, .col-lg-5, .col-xs-6, .col-sm-6, .col-md-6, .col-lg-6, .col-xs-7, .col-sm-7, .col-md-7, .col-lg-7, .col-xs-8, .col-sm-8, .col-md-8, .col-lg-8, .col-xs-9, .col-sm-9, .col-md-9, .col-lg-9, .col-xs-10, .col-sm-10, .col-md-10, .col-lg-10, .col-xs-11, .col-sm-11, .col-md-11, .col-lg-11, .col-xs-12, .col-sm-12, .col-md-12, .col-lg-12 {
+    position: relative;
+    min-height: 1px;
+    float: left;
+    padding-right: 10px;
+    padding-left: 10px;
+}
+
+.col-middle {
+    margin-top: 5%;
+}
+
+.text-center {
+    text-align: center;
+}
+
+p {
+    margin: 0 0 10px;
+}
+
+img {
+    vertical-align: middle;
+    border: 0;
+}
+
+.text-error {
+    background: rgba(255,255,255,0.9);
+    color: #000;
+    padding: 25px 0;
+    margin: 120px 0;
+}
+
+h1 {
+    margin-top: 10px;
+    margin-bottom: 10px;
+    font-family: 'Montserrat', sans-serif;
+    font-size: 36px;
+    font-weight: 500;
+    line-height: 1.1;
+    color: inherit;
+    margin: 0.67em 0;
+}
+b, strong {
+    font-weight: bold;
+}
+.mid_center {
+    width: 370px;
+    margin: 0 auto;
+    text-align: center;
+    padding: 10px 20px;
+}
+.btn-success {
+    border: none;
+    box-shadow: none;
+    border-radius: 2px;
+    font-size: 1.4rem;
+    cursor: pointer;
+    background: #1fbc99;
+    border: 1px solid #1ba385;
+}
+
+.buttons, button, .btn {
+    margin-right: 5px;
+}
+#push, #footer {
+    height: 60px;
+    text-align: center;
+    color: #fff;
+}
\ No newline at end of file
diff --git a/gulliver/methods/errors/block.php b/gulliver/methods/errors/block.php
new file mode 100644
index 000000000..19b4a3106
--- /dev/null
+++ b/gulliver/methods/errors/block.php
@@ -0,0 +1,105 @@
+<?php
+if (function_exists("http_response_code")) {
+    http_response_code(200);
+}
+
+$http = (isset($_SERVER["HTTPS"]) && $_SERVER["HTTPS"] == "on") ? "https" : "http";
+$host = $_SERVER["SERVER_NAME"] . (($_SERVER["SERVER_PORT"] != "80") ? ":" . $_SERVER["SERVER_PORT"] : "");
+
+$urlLogin = $http . "://" . $host . "/sys/en/neoclassic/login/login";
+$urlHome = $urlLogin;
+
+if (isset($_GET["url"]) && $_GET["url"] != "") {
+
+    $url = urldecode($_GET["url"]);
+    $url = explode("/", $url);
+
+    $sysSys = "";
+    $sysLang = "";
+    $sysSkin = "";
+
+    if (isset($url[1]) && preg_match("/^sys(.+)$/", $url[1], $match)) {
+        $sysSys = $match[1];
+
+        // Check if sys path exists
+        $checkDir = PATH_DATA . "sites/" . $sysSys;
+        if (!is_dir($checkDir)) {
+            $sysSys = '';
+        }
+    }
+
+
+    if (isset($url[2])) {
+        $sysLang = $url[2];
+    }
+
+    if (isset($url[3])) {
+        $sysSkin = $url[3];
+
+        // Check if sys path exists
+        $checkDir = PATH_SKIN_ENGINE . $sysSkin;
+        if (!is_dir($checkDir)) {
+            // Try this again
+            $checkDir = PATH_CUSTOM_SKINS . $sysSkin;
+            if (!is_dir($checkDir)) {
+                $sysSkin = '';
+            }
+        }
+    }
+
+    if ($sysSys != "" && $sysLang != "" && $sysSkin != "") {
+        $urlLogin = $http . "://" . $host . "/sys" . $sysSys . "/" . $sysLang . "/" . $sysSkin . "/login/login";
+        $urlHome = $http . "://" . $host . "/sys" . $sysSys . "/" . $sysLang . "/" . $sysSkin . "/cases/main";
+    }
+}
+
+?>
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <link rel="shortcut icon" href="../images/favicon.ico" type="image/x-icon"/>
+    <link href="../lib/pmdynaform/libs/bootstrap-3.1.1/css/bootstrap.min.css" rel="stylesheet">
+    <link href="block.css" type="text/css" rel="stylesheet"/>
+</head>
+<body class="nav-md special-page" style="margin: 0px; overflow: auto;">
+<div class="container body ">
+
+    <div class="main_container">
+
+        <!-- page content -->
+        <div class="col-md-12">
+            <div class="col-middle">
+                <div class="text-center">
+                    <p><img src="images/fa-hand-pointer-o.png"></p>
+                </div>
+                <div class="text-center text-error">
+                    <h1>Hi there, please check your tabs!</h1>
+                    <p><b>A browser instance of ProcessMaker is actually open.</b> You can start only one at the time.
+                        For more information:
+                    </p>
+                    <div class="mid_center">
+                        <a type="button" class="btn btn-success btn-lg" href="http://wiki.processmaker.com">Click here
+                            to see our Wiki</a>
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+<!-- /page content -->
+
+<!-- footer content -->
+<div id="footer">
+    <div class="container">
+        <p><img src="images/processmaker.logow.png"></p>
+        <p class="muted credit">Supplied free of charge with no support, certification, warranty, maintenance nor indemnity by ProcessMaker and its Certified Partners<br>
+            Copyright © 2003-<?php echo date('Y');?> ProcessMaker, Inc. All rights reserved. </p>
+    </div>
+</div>
+
+</body>
+</html>
diff --git a/gulliver/methods/errors/images/fa-hand-pointer-o.png b/gulliver/methods/errors/images/fa-hand-pointer-o.png
new file mode 100644
index 000000000..feac7ccc2
Binary files /dev/null and b/gulliver/methods/errors/images/fa-hand-pointer-o.png differ
diff --git a/gulliver/methods/errors/images/processmaker.logow.png b/gulliver/methods/errors/images/processmaker.logow.png
new file mode 100644
index 000000000..f8981bd46
Binary files /dev/null and b/gulliver/methods/errors/images/processmaker.logow.png differ
diff --git a/workflow/engine/js/src/Sessions.js b/workflow/engine/js/src/Sessions.js
index 532b2bdd8..bb101da4b 100644
--- a/workflow/engine/js/src/Sessions.js
+++ b/workflow/engine/js/src/Sessions.js
@@ -7,6 +7,7 @@ PM.Sessions = (function () {
         if (window.location.pathname.indexOf("login") === -1 &&
             window.location.pathname.indexOf("sysLogin") === -1 &&
             window.location.pathname.indexOf("authentication") === -1 &&
+            window.location.pathname.indexOf("/sys/") === -1 &&
             this.getCookie('PM-TabPrimary') !== '101010010') {
             this.isClose = (this.getLabel('mainWindowClose') === "true");
             if (this.isClose && parent.parent.parent.window.name === "") {