Undefined class constant ‘XML_NODE_PRODUCT_MAX_DIMENSION’ in app/design/adminhtml/default/default/template/catalog/product/helper/gallery.phtml on line 111

Any attempt to edit product at Catalog > Manage Products in Magento backend results in a blank page and logs the following fatal error after SUPEE-8788 patch or Magento upgrade:

Fatal error: Undefined class constant 'XML_NODE_PRODUCT_MAX_DIMENSION' in
app/design/adminhtml/default/default/template/catalog/product/helper/gallery.phtml
 on line 111

Cause

XML_NODE_PRODUCT_MAX_DIMENSION constant used in the new app/design/adminhtml/default/default/template/catalog/product/helper/gallery.phtml is defined in app/code/core/Mage/Catalog/Helper/Image.php with SUPEE-8788 applied:

--- app/code/core/Mage/Catalog/Helper/Image.php
+++ app/code/core/Mage/Catalog/Helper/Image.php
@@ -31,6 +31,8 @@
  */
 class Mage_Catalog_Helper_Image extends Mage_Core_Helper_Abstract
 {
+    const XML_NODE_PRODUCT_MAX_DIMENSION = 'catalog/product_image/max_dimension';

As the error says it can not find the constant definition, which may be possible due to one of the following reasons:

• app/code/core/Mage/Catalog/Helper/Image.php is overridden with a local copy in app/code/local/Mage/Catalog/Helper/Image.php or app/code/community/Mage/Catalog/Helper/Image.php
• Magento Compiler is enabled and compiler cache was not cleared after SUPEE-8788 patch installation or upgrade
• PHP OpCode cache is in use

Solution

• Check if XML_NODE_PRODUCT_MAX_DIMENSION is defined in app/code/core/Mage/Catalog/Helper/Image.php:

  $ grep XML_NODE_PRODUCT_MAX_DIMENSION app/code/core/Mage/Catalog/Helper/Image.php 
      const XML_NODE_PRODUCT_MAX_DIMENSION = 'catalog/product_image/max_dimension';
          $maxDimension = Mage::getStoreConfig(self::XML_NODE_PRODUCT_MAX_DIMENSION);
  

  Re-apply SUPEE-8788 patch if you see empty output.
• Check if there are local overrides in app/code/local/Mage/Catalog/Helper/Image.php or app/code/community/Mage/Catalog/Helper/Image.php:

  $ ls -la app/code/{local,community}/Mage/Catalog/Helper/Image.php
  

  Apply corresponding changes from SUPEE-8788 to any local overrides as well if there are any.
• Disable Magento Compiler or clear Compiler cache
• Flush PHP OpCode cache

If you have any difficulties with solving this problem or got a similar one, please let us know in comments below, so we can find the solution together.

Posted in: Fatal errors