In Case anybody having same error try replacing entire update_product.php with this code:
This is currently working for me.
But remember you put your FaceBook Info

PHP Code:
<?php
/**
 * @package admin
 * @copyright Copyright 2003-2011 Zen Cart Development Team
 * @copyright Portions Copyright 2003 osCommerce
 * @license http://www.zen-cart.com/license/2_0.txt GNU Public License V2.0
 * @version $Id: update_product.php 18695 2011-05-04 05:24:19Z drbyte $
 */
  
if (!defined('IS_ADMIN_FLAG')) {
    die(
'Illegal Access');
  }
  if (isset(
$_GET['pID'])) $products_id zen_db_prepare_input($_GET['pID']);
  if (isset(
$_POST['edit_x']) || isset($_POST['edit_y'])) {
    
$action 'new_product';
  } elseif (
$_POST['products_model'] . $_POST['products_url'] . $_POST['products_name'] . $_POST['products_description'] != '') {
    
$products_date_available zen_db_prepare_input($_POST['products_date_available']);

    
$products_date_available = (date('Y-m-d') < $products_date_available) ? $products_date_available 'null';

    
// Data-cleaning to prevent MySQL5 data-type mismatch errors:
    
$tmp_value zen_db_prepare_input($_POST['products_quantity']);
    
$products_quantity = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? $tmp_value;
    
$tmp_value zen_db_prepare_input($_POST['products_price']);
    
$products_price = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? $tmp_value;
    
$tmp_value zen_db_prepare_input($_POST['products_weight']);
    
$products_weight = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? $tmp_value;
    
$tmp_value zen_db_prepare_input($_POST['manufacturers_id']);
    
$manufacturers_id = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? $tmp_value;

    
$sql_data_array = array('products_quantity' => $products_quantity,
                            
'products_type' => zen_db_prepare_input($_GET['product_type']),
                            
'products_model' => zen_db_prepare_input($_POST['products_model']),
                            
'products_price' => $products_price,
                            
'products_date_available' => $products_date_available,
                            
'products_weight' => $products_weight,
                            
'products_status' => zen_db_prepare_input((int)$_POST['products_status']),
                            
'products_virtual' => zen_db_prepare_input((int)$_POST['products_virtual']),
                            
'products_tax_class_id' => zen_db_prepare_input((int)$_POST['products_tax_class_id']),
                            
'manufacturers_id' => $manufacturers_id,
                            
'products_quantity_order_min' => zen_db_prepare_input($_POST['products_quantity_order_min']),
                            
'products_quantity_order_units' => zen_db_prepare_input($_POST['products_quantity_order_units']),
                            
'products_priced_by_attribute' => zen_db_prepare_input($_POST['products_priced_by_attribute']),
                            
'product_is_free' => zen_db_prepare_input((int)$_POST['product_is_free']),
                            
'product_is_call' => zen_db_prepare_input((int)$_POST['product_is_call']),
                            
'products_quantity_mixed' => zen_db_prepare_input($_POST['products_quantity_mixed']),
                            
'product_is_always_free_shipping' => zen_db_prepare_input((int)$_POST['product_is_always_free_shipping']),
                            
'products_qty_box_status' => zen_db_prepare_input($_POST['products_qty_box_status']),
                            
'products_quantity_order_max' => zen_db_prepare_input($_POST['products_quantity_order_max']),
                            
'products_sort_order' => (int)zen_db_prepare_input($_POST['products_sort_order']),
                            
'products_discount_type' => zen_db_prepare_input($_POST['products_discount_type']),
                            
'products_discount_type_from' => zen_db_prepare_input($_POST['products_discount_type_from']),
                            
'products_price_sorter' => zen_db_prepare_input($_POST['products_price_sorter'])
                            );

    
// when set to none remove from database
    // is out dated for browsers use radio only
      
$sql_data_array['products_image'] = zen_db_prepare_input($_POST['products_image']);
      
$new_image'true';

    if (
$_POST['image_delete'] == 1) {
      
$sql_data_array['products_image'] = '';
      
$new_image'false';
    }

if (
$_POST['image_delete'] == 1) {
      
$sql_data_array['products_image'] = '';
      
$new_image'false';
}

    if (
$action == 'insert_product') {
      
$insert_sql_data = array( 'products_date_added' => 'now()',
                                
'master_categories_id' => (int)$current_category_id);

      
$sql_data_array array_merge($sql_data_array$insert_sql_data);

      
zen_db_perform(TABLE_PRODUCTS$sql_data_array);
      
$products_id zen_db_insert_id();

      
// reset products_price_sorter for searches etc.
      
zen_update_products_price_sorter($products_id);

      
$db->Execute("insert into " TABLE_PRODUCTS_TO_CATEGORIES "
                    (products_id, categories_id)
                    values ('" 
. (int)$products_id "', '" . (int)$current_category_id "')");

      
///////////////////////////////////////////////////////
      //// INSERT PRODUCT-TYPE-SPECIFIC *INSERTS* HERE //////
          //AutoFacebook
          
$app_id "Your App_ID Here"//given when you created app
          
$app_secret "Your App Secret Code Here"//given when you created app
          
$page_id "Page ID Here"//obtained from running facebook_authorization.php from your browser
          
$page_token "Page Token Here"//long number obtained from facebook_authorization.php
          
$store_name "Your Store"// store name i.e. "Mary's Car Shop", or "MikesCupcakes.com."
          
$store_url 'http://www.yourdomain.com'//path to your store without the trailing "/"
          
$cur '$'//change to your currency symbol($, €, £, ¥, etc.). Assumes symbol comes in front of numbers
          
$new_message "New Product Added";  // change to whatever or leave the same. i.e "New Cupcake!"

          // No Need to edit below here.
          
$prod_image $store_url "/images/" $_POST['products_image'];
          
//webelity.com fixed number formating issues 11-4-2013 - 2.4   
      //$price = $products_price;
      
$price number_format($products_price2'.''');          
      
$prod_url $store_url '/index.php?main_page=product_info&cPath=' $current_category_id '&products_id=' $products_id;
          
$prod_name $_POST['products_name'][$_SESSION['languages_id']];
          
//webelity.com changed this line below to strip html tags from descriptions (Facebook does not support standard html input on descriptions via api calls)
          
$prod_description $_POST['products_description'][$_SESSION['languages_id']];

          
//webelity.com changed this line below to strip html tags from descriptions (Facebook does not support standard html input on descriptions via api calls)
          
$info_strip preg_replace('/(<\/[^>]+?>)(<[^>\/][^>]*?>)/''$1 $2'$prod_description);
          
$description_stripped strip_tags($info_strip);

          
//webelity.com 1-15-2012 added check to insure length does not reach the 10,000 character limit on descriptions in facebook.
          
$charset 'UTF-8';
          
$no_description 0;
          
$length 9996;
          if(
mb_strlen($description_stripped$charset) > $length) {
            
$facebook_description mb_substr($description_stripped0$length$charset) . '...';
          }
          elseif(
mb_strlen($description_stripped$charset) == $no_description)
          {
            
$facebook_description "No description provided for this product.";
          }
          else
          {
              
$facebook_description $description_stripped;
          }

          include_once 
'facebook/facebook.php';

          
$facebook = new Facebook(array(
              
'appId'  => $app_id,
              
'secret' => $app_secret,
              
'cookie' => true, )
          );
          
// webelity.com modfied currancy and price information and added facebook_description to lower array
          
$attachment = array(
              
'access_token'      =>  $page_token,
              
'message'           =>  $new_message " - " $prod_name,
              
'name'              =>  $prod_name,
              
'link'              =>  $prod_url,
              
'caption'           =>  'Price: ' $cur $price,
              
'description'       =>  $facebook_description,
              
'picture'           =>  $prod_image
          
);
          try {
            
$status $facebook->api($page_id.'/feed''post'$attachment);
            
$messageStack->add_session('Facebook was successfully updated!''success');
          }
          catch (
FacebookApiException $fbe){
            
$fberror $fbe->result['error']['message'];
            
$messageStack->add_session('Facebook Error: '.$fberror'error');
          }


      
////    *END OF PRODUCT-TYPE-SPECIFIC INSERTS* ////////
      ///////////////////////////////////////////////////////
    
} elseif ($action == 'update_product') {
      
$update_sql_data = array( 'products_last_modified' => 'now()',
                                
'master_categories_id' => ($_POST['master_category'] > zen_db_prepare_input($_POST['master_category']) : zen_db_prepare_input($_POST['master_categories_id'])));

      
$sql_data_array array_merge($sql_data_array$update_sql_data);

      
zen_db_perform(TABLE_PRODUCTS$sql_data_array'update'"products_id = '" . (int)$products_id "'");

      
// reset products_price_sorter for searches etc.
      
zen_update_products_price_sorter((int)$products_id);

      
///////////////////////////////////////////////////////
      //// INSERT PRODUCT-TYPE-SPECIFIC *UPDATES* HERE //////
          //AutoFacebook
          
$app_id "Your App_ID Here"//given when you created app
          
$app_secret "Your App Secret Code Here"//given when you created app
          
$page_id "Page ID Here"//obtained from running facebook_authorization.php from your browser
          
$page_token "Page Token Here"//long number obtained from facebook_authorization.php
          
$store_name "Your Store"// store name i.e. "Mary's Car Shop", or "MikesCupcakes.com."
          
$store_url 'http://www.yourdomain.com'//path to your store without the trailing "/"
          
$cur '$'//change to your currency symbol($, €, £, ¥, etc.). Assumes symbol comes in front of numbers
          
$new_message "New Product Added";  // change to whatever or leave the same. i.e "New Cupcake!"

          // No Need to edit below here.
          
$prod_image $store_url "/images/" $_POST['products_image'];
          
//webelity.com fixed number formating issues 11-4-2013 - 2.4   
      //$price = $products_price;
      
$price number_format($products_price2'.''');          
      
$prod_url $store_url '/index.php?main_page=product_info&cPath=' $current_category_id '&products_id=' $products_id;
          
$prod_name $_POST['products_name'][$_SESSION['languages_id']];
          
//webelity.com changed this line below to strip html tags from descriptions (Facebook does not support standard html input on descriptions via api calls)
          
$prod_description $_POST['products_description'][$_SESSION['languages_id']];

          
//webelity.com changed this line below to strip html tags from descriptions (Facebook does not support standard html input on descriptions via api calls)
          
$info_strip preg_replace('/(<\/[^>]+?>)(<[^>\/][^>]*?>)/''$1 $2'$prod_description);
          
$description_stripped strip_tags($info_strip);

          
//webelity.com 1-15-2012 added check to insure length does not reach the 10,000 character limit on descriptions in facebook.
          
$charset 'UTF-8';
          
$no_description 0;
          
$length 9996;
          if(
mb_strlen($description_stripped$charset) > $length) {
            
$facebook_description mb_substr($description_stripped0$length$charset) . '...';
          }
          elseif(
mb_strlen($description_stripped$charset) == $no_description)
          {
            
$facebook_description "No description provided for this product.";
          }
          else
          {
              
$facebook_description $description_stripped;
          }

          include_once 
'facebook/facebook.php';

          
$facebook = new Facebook(array(
              
'appId'  => $app_id,
              
'secret' => $app_secret,
              
'cookie' => true, )
          );
          
// webelity.com modfied currancy and price information and added facebook_description to lower array
          
$attachment = array(
              
'access_token'      =>  $page_token,
              
'message'           =>  $new_message " - " $prod_name,
              
'name'              =>  $prod_name,
              
'link'              =>  $prod_url,
              
'caption'           =>  'Price: ' $cur $price,
              
'description'       =>  $facebook_description,
              
'picture'           =>  $prod_image
          
);
          try {
            
$status $facebook->api($page_id.'/feed''post'$attachment);
            
$messageStack->add_session('Facebook was successfully updated!''success');
          }
          catch (
FacebookApiException $fbe){
            
$fberror $fbe->result['error']['message'];
            
$messageStack->add_session('Facebook Error: '.$fberror'error');
          }


      
////    *END OF PRODUCT-TYPE-SPECIFIC UPDATES* ////////
      ///////////////////////////////////////////////////////
    
}

    
$languages zen_get_languages();
    for (
$i=0$n=sizeof($languages); $i<$n$i++) {
      
$language_id $languages[$i]['id'];

      
$sql_data_array = array('products_name' => zen_db_prepare_input($_POST['products_name'][$language_id]),
                              
'products_description' => zen_db_prepare_input($_POST['products_description'][$language_id]),
                              
'products_url' => zen_db_prepare_input($_POST['products_url'][$language_id]));

      if (
$action == 'insert_product') {
        
$insert_sql_data = array('products_id' => (int)$products_id,
                                 
'language_id' => (int)$language_id);

        
$sql_data_array array_merge($sql_data_array$insert_sql_data);

        
zen_db_perform(TABLE_PRODUCTS_DESCRIPTION$sql_data_array);
      } elseif (
$action == 'update_product') {
        
zen_db_perform(TABLE_PRODUCTS_DESCRIPTION$sql_data_array'update'"products_id = '" . (int)$products_id "' and language_id = '" . (int)$language_id "'");
      }
    }

    
// add meta tags
    
$languages zen_get_languages();
    for (
$i=0$n=sizeof($languages); $i<$n$i++) {
      
$language_id $languages[$i]['id'];

      
$sql_data_array = array('metatags_title' => zen_db_prepare_input($_POST['metatags_title'][$language_id]),
                              
'metatags_keywords' => zen_db_prepare_input($_POST['metatags_keywords'][$language_id]),
                              
'metatags_description' => zen_db_prepare_input($_POST['metatags_description'][$language_id]));

      if (
$action == 'insert_product_meta_tags') {

        
$insert_sql_data = array('products_id' => (int)$products_id,
                                 
'language_id' => (int)$language_id);

        
$sql_data_array array_merge($sql_data_array$insert_sql_data);

        
zen_db_perform(TABLE_META_TAGS_PRODUCTS_DESCRIPTION$sql_data_array);
      } elseif (
$action == 'update_product_meta_tags') {
        
zen_db_perform(TABLE_META_TAGS_PRODUCTS_DESCRIPTION$sql_data_array'update'"products_id = '" . (int)$products_id "' and language_id = '" . (int)$language_id "'");
      }
    }


    
// future image handler code
    
define('IMAGE_MANAGER_HANDLER'0);
    
define('DIR_IMAGEMAGICK''');
    if (
$new_image == 'true' and IMAGE_MANAGER_HANDLER >= 1) {
      
$srcDIR_FS_CATALOG DIR_WS_IMAGES zen_get_products_image((int)$products_id);
      
$filename_small$src;
      
preg_match("/.*\/(.*)\.(\w*)$/"$src$fname);
      list(
$oiwidth$oiheight$oitype) = getimagesize($src);

      
$small_widthSMALL_IMAGE_WIDTH;
      
$small_heightSMALL_IMAGE_HEIGHT;
      
$medium_widthMEDIUM_IMAGE_WIDTH;
      
$medium_heightMEDIUM_IMAGE_HEIGHT;
      
$large_widthLARGE_IMAGE_WIDTH;
      
$large_heightLARGE_IMAGE_HEIGHT;

      
$k max($oiheight $small_height$oiwidth $small_width); //use smallest size
      
$small_width round($oiwidth $k);
      
$small_height round($oiheight $k);

      
$k max($oiheight $medium_height$oiwidth $medium_width); //use smallest size
      
$medium_width round($oiwidth $k);
      
$medium_height round($oiheight $k);

      
$large_width$oiwidth;
      
$large_height$oiheight;

      
$products_image zen_get_products_image((int)$products_id);
      
$products_image_extension substr($products_imagestrrpos($products_image'.'));
      
$products_image_base preg_replace('/'.$products_image_extension.'/'''$products_image);

      
$filename_medium DIR_FS_CATALOG DIR_WS_IMAGES 'medium/' $products_image_base IMAGE_SUFFIX_MEDIUM '.' $fname[2];
      
$filename_large DIR_FS_CATALOG DIR_WS_IMAGES 'large/' $products_image_base IMAGE_SUFFIX_LARGE '.' $fname[2];

      
// ImageMagick
      
if (IMAGE_MANAGER_HANDLER == '1') {
        
copy($src$filename_large);
        
copy($src$filename_medium);
        
exec(DIR_IMAGEMAGICK "mogrify -geometry " $large_width " " $filename_large);
        
exec(DIR_IMAGEMAGICK "mogrify -geometry " $medium_width " " $filename_medium);
        
exec(DIR_IMAGEMAGICK "mogrify -geometry " $small_width " " $filename_small);
      }
    }

    
zen_redirect(zen_href_link(FILENAME_CATEGORIES'cPath=' $cPath '&pID=' $products_id . (isset($_GET['page']) ? '&page=' $_GET['page'] : '') . (isset($_POST['search']) ? '&search=' $_POST['search'] : '') ));
  } else {
    
$messageStack->add_session(ERROR_NO_DATA_TO_SAVE'error');
    
zen_redirect(zen_href_link(FILENAME_CATEGORIES'cPath=' $cPath '&pID=' $products_id . (isset($_GET['page']) ? '&page=' $_GET['page'] : '') . (isset($_POST['search']) ? '&search=' $_POST['search'] : '') ));
  }