Title: PHP Warning: Undefined array key “extension”
Last modified: October 24, 2024

---

# PHP Warning: Undefined array key “extension”

 *  Resolved [petertely](https://wordpress.org/support/users/petertely/)
 * (@petertely)
 * [1 year, 7 months ago](https://wordpress.org/support/topic/php-warning-508/)
 * Hi,
 * “Regenerate all entries” and “Regenerate all entries (optimized)” are not completing.
   The progress freezes after a certain time.
 * Errors in debug.log:
    - PHP Warning: Undefined array key “extension” in /wp-content/plugins/wp-retina-
      2x/classes/core.php on line 1675
    - PHP Warning: Undefined array key “extension” in /wp-content/plugins/wp-retina-
      2x/classes/core.php on line 1754
    - PHP Warning: Undefined array key “extension” in /wp-content/plugins/wp-retina-
      2x/classes/core.php on line 1848
 * Environment:
 * WordPress 6.6.2
   WooCommerce 9.3.3PHP 8.2.24max_execution_time : 14400memory_limit:
   512Mwp_memory_limit : 256Mwp_max_memory_limit : 512M
 * Bonus question:
 * What is the difference between “Regenerate all entries” and “Regenerate all entries(
   optimized)”? (I couldn’t find the information in the documentation).
 * Thank you in advance.

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Support [Val Meow](https://wordpress.org/support/users/valwa/)
 * (@valwa)
 * [1 year, 7 months ago](https://wordpress.org/support/topic/php-warning-508/#post-18098090)
 * Hey [@petertely](https://wordpress.org/support/users/petertely/)! 👋
 * This is a warning message that you can safely ignore. If the process freezes,
   it likely indicates an error. Check your PHP logs for any fatal errors that might
   explain which part of the process is failing. If there’s no error, your server
   might have security rules limiting the number of requests allowed in a given 
   time frame, and bulk regeneration could exceed these limits. To troubleshoot,
   monitor your network activity during the process to see the server’s response.
 * The “Regenerate All Entries” option deletes all thumbnails and recreates them,
   while the “Optimize” option scans existing thumbnails and only regenerates the
   necessary ones, making it more efficient for bulk-processing a large number of
   images.
 *  Thread Starter [petertely](https://wordpress.org/support/users/petertely/)
 * (@petertely)
 * [1 year, 7 months ago](https://wordpress.org/support/topic/php-warning-508/#post-18098269)
 * Hi Val Meow,
 * Thanks for your response and for explaining the difference between the two options.
 * Even if the PHP warning isn’t critical, will it be fixed in an upcoming update?
   I like to keep my debug.log clean 😉
 * As for the mass regeneration block, I thought it was due to a low “max_execution_time”.
   I increased it to 14400, but it didn’t change anything. My host (O2Switch) is
   known to be reliable in France. During the attempts, I don’t see any errors other
   than the ones already mentioned.
 * Thanks

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘PHP Warning: Undefined array key “extension”’ is closed to new replies.

 * ![](https://ps.w.org/wp-retina-2x/assets/icon-256x256.png?rev=2597316)
 * [Perfect Images: Regenerate Thumbnails, Image Sizes, WebP & AVIF](https://wordpress.org/plugins/wp-retina-2x/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-retina-2x/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-retina-2x/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-retina-2x/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-retina-2x/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wp-retina-2x/reviews/)

 * 2 replies
 * 2 participants
 * Last reply from: [petertely](https://wordpress.org/support/users/petertely/)
 * Last activity: [1 year, 7 months ago](https://wordpress.org/support/topic/php-warning-508/#post-18098269)
 * Status: resolved