Magento 1.9.3.2 checkout not working after applying SUPEE 10572 patch

Question

The regular one-page checkout (/checkout/onepage/) has stopped working following applying the 3 latest SUPEE patches.

exception 'Mage_Core_Exception' with message 'Invalid block type: ' in /var/www/html/myshop/app/Mage.php:595
Stack trace:
#0 /var/www/html/msyhop/app/code/core/Mage/Core/Model/Layout.php(495): Mage::throwException('Invalid block t...')
#1 /var/www/html/myshop/app/code/core/Mage/Core/Model/Layout.php(437): Mage_Core_Model_Layout->_getBlockInstance('', Array)
#2 /var/www/html/myshop/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout->createBlock('', 'root')
#3 /var/www/html/myshop/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout->addBlock('', 'root')
#4 /var/www/html/myshop/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_La$
#5 /var/www/html/myshop/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout->generateBlocks()
#6 /var/www/html/myshop/app/code/core/Mage/Core/Controller/Varien/Action.php(269): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#7 /var/www/html/myshop/app/code/core/Mage/Checkout/controllers/CartController.php(194): Mage_Core_Controller_Varien_Action->loadLayout()
#8 /var/www/html/myshop/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Checkout_CartController->indexAction()
#9 /var/www/html/myshop/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('index')
#10 /var/www/html/myshop/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#11 /var/www/html/myshop/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#12 /var/www/html/myshop/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#13 /var/www/html/myshop/index.php(100): Mage::run('', 'store')
#14 {main}

Points #1,#2,and #3 all have an empty string in the block calls. This would suggest to me that a block has been declared/called in the layout with no type. However I cannot find an empty block declaration so far.

Does anyone have any suggestions how to speedily debug this type of issue?

Thanks

UPDATE Actually this turned out to be a problem with the php version. I tracked the error down to app/code/core/Mage/Checkout/Model/Type/Onepage.php

Parse error: syntax error, unexpected '[' in /var/www/html/myshop/app/code/core/Mage/Checkout/Model/Type/Onepage.php on line 732
Array
(
    [type] => 4
    [message] => syntax error, unexpected '['
    [file] => /var/www/html/msyhop/app/code/core/Mage/Checkout/Model/Type/Onepage.php
    [line] => 732
)

The line here uses an array reference syntax not valid for php 5.3 (which my server was) which has appeared after doing applying SUPEE-10572. By upgrading to 5.4 the checkout now works.

Answer 1

Actually this turned out to be a problem with the php version. I tracked the error down to app/code/core/Mage/Checkout/Model/Type/Onepage.php by turning on PHP show all errors and using a fatal_handler function to get the last error message. The captured error was

Parse error: syntax error, unexpected '[' in /var/www/html/myshop/app/code/core/Mage/Checkout/Model/Type/Onepage.php on line 732
Array
(
    [type] => 4
    [message] => syntax error, unexpected '['
    [file] => /var/www/html/msyhop/app/code/core/Mage/Checkout/Model/Type/Onepage.php
    [line] => 732
)

The line here uses an array reference syntax not valid for php 5.3 (which my server was) which has appeared after doing applying SUPEE-10572. By upgrading to 5.4 the checkout now works.

For reference, here is the handy bit of code I use at the top of my index.php file for debugging problems:

<?php
//...
$errorSHOW = false;


function fatal_handler() {
    $error = error_get_last();
    echo "<pre>";
    print_r($error);
    echo "</pre>";
}

if($errorSHOW){ //THIS WILL CAUSE AN ERROR TO ALWAYS SHOW.  THIS WILL BREAK JSON AND OTHER SCRIPTS
    ini_set('display_errors',1);
    error_reporting(E_ALL);
    register_shutdown_function("fatal_handler");
}
...//
?>