Add this file for printing errors in magento (src/errors/local.xml)

local.xml

<?xml version="1.0"?>
<!--
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Academic Free License (AFL 3.0)
 * that is bundled with this package in the file LICENSE_AFL.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/afl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to [email protected] so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Errors
 * @copyright   Copyright (c) 2006-2016 X.commerce, Inc. and affiliates (http://www.magento.com)
 * @license     http://opensource.org/licenses/afl-3.0.php  Academic Free License (AFL 3.0)
 */
-->
<config>
    <skin>default</skin>
    <report>
        <!--
            "action" can be set to "print" to show exception on screen and "email"
            to send exception on specified email
        -->
        <action>print</action>
        <!--
            in "subject" you can set subject of email
        -->
        <subject>Store Debug Information</subject>
        <!--
            "email_address" admin email address
        -->
        <email_address></email_address>
        <!--
            "trash" is handle about trace info
            value "leave" is for store on disk
            value "delete" is for cleaning
        -->
        <trash>leave</trash>
    </report>
</config>