Undefined offset in Abstract.php / Continue to checkout button doesn't work

Question

I have upgraded to Magento 1.9.2 and am using the rwd theme (with a few tweaks). I have checkout as guest enabled. When you get to the stage in ordering where you choose between 'Checkout as Guest' or 'Register and Checkout', no matter which option you choose the continue button does not work. I enabled logging and the following errors were in the log although they don't seem to be created by clicking the continue button as such, i.e. clicking the button repeatedly does not create any more errors. Could they nonetheless be the reason the button isn't working?:

 ERR (3): Notice: Undefined offset: 1 in /var/www/html/magento/lib/Zend/Db/Adapter/Abstract.php on line 814

and

 ERR (3): Notice: Undefined offset: 1 in /var/www/html/magento/app/code/local/Bintime/Sinchimport/Model/Layer/Filter/Price.php on line 146

The code around line 814 in Abstract.php is:

 public function fetchPairs($sql, $bind = array())
 {
      $stmt = $this->query($sql, $bind);
      $data = array();
      while ($row = $stmt->fetch(Zend_Db::FETCH_NUM)) {
            $data[$row[0]] = $row[1];   //This is line 814
      }
      return $data;
 }

The code around line 146 in Price.php is

 protected function _getItemsData()
 {
      $import=Mage::getModel('sinchimport/sinch');
      $price_breaks=$import->price_breaks_filter;

      if(strstr($price_breaks, ';')){
          $price_ranges = explode(';', $price_breaks);

          foreach ($price_ranges as $price_range) {
                $price_range_value=trim($price_range);
                if($price_range && $price_range!=''){

                     $price_range = explode('-', $price_range);
                     list($minPrice, $maxPrice) = $price_range;  // This is line 146
                     if(((int)$minPrice || $minPrice==0) && ((int)$maxPrice || $maxPrice=='*')){
                          $count=$this->_getResource()->getCountMinMaxPrice($this, $minPrice, $maxPrice);
                          if($count){
                              $data[] = array(
                                      'label' => $this->_renderItemLabelMinMaxPrice($minPrice, $maxPrice),
                                      'value' =>$price_range_value,
                                      'count' => $count,
                                       );
                           }
                      }
                }
           }
           if($data){
               return $data;
           }
       }

       $range         = $this->getPriceRange();
       $dbRanges      = $this->getRangeItemCounts($range);
       $data          = array();

       foreach ($dbRanges as $index=>$count) {
           $data[] = array(
                   'label' => $this->_renderItemLabel($range, $index),
                   'value' => $index . ',' . $range,
                   'count' => $count,
                   );
        }

        return $data;
  }

Answer 1

Turn on SQL Logging.

Example in Lib/Varien/Db/Adapter/Pdo/Mysql.php:

protected $_debug               = true;
protected $_logAllQueries       = true;
protected $_logCallStack        = true;

Then turn on errors/reporting and put Magento in developers mode, so it will raise a exception and stop executing in index.php.

$_SERVER['MAGE_IS_DEVELOPER_MODE'] = true;
ini_set('display_errors', 1);

Flush Cache 'full' (just to be on the safe side) and reload page.

Then open your log file in /var/log/ and scroll down to the last SELECT ... query and look at it. Than try this out on your database, and look if its a warning or it has two field pairs. Like KEY + VALUE >== $data[$row[0]] = $row[1];

Good luck and happy hacking !