Title: PHP Fatal error: Uncaught TypeError
Last modified: February 19, 2026

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# PHP Fatal error: Uncaught TypeError

 *  Resolved [jannis01](https://wordpress.org/support/users/jannis01/)
 * (@jannis01)
 * [3 months, 3 weeks ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-typeerror-19/)
 * Hello,
   we use the LS-Cache Version 7.7 and when we try to duplicate a product
   on our eshop with a the **Duplicate Page** plugin, WordPress crashes with a critical
   error and debug log shows the following error:
 *     ```wp-block-code
       [19-Feb-2026 16:43:47 UTC] PHP Fatal error:  Uncaught TypeError: Automattic\WooCommerce\Internal\Caches\VersionStringGenerator::delete_version(): Return value must be of type bool, null returned in  /home/wordpress/public_html/wp-content/plugins/woocommerce/src/Internal/Caches/VersionStringGenerator.php:155Stack trace:#0  /home/wordpress/public_html/wp-content/plugins/woocommerce/src/Internal/Caches/ProductVersionStringInvalidator.php(602): Automattic\WooCommerce\Internal\Caches\VersionStringGenerator->delete_version()#1  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/data-stores/class-wc-product-variable-data-store-cpt.php(759): Automattic\WooCommerce\Internal\Caches\ProductVersionStringInvalidator->invalidate()#2  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/class-wc-data-store.php(224): WC_Product_Variable_Data_Store_CPT->sync_variation_names()#3  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/class-wc-product-variable.php(532): WC_Data_Store->__call()#4  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/abstracts/abstract-wc-product.php(1507): WC_Product_Variable->after_data_store_save_or_update()#5  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/admin/class-wc-admin-duplicate-product.php(189): WC_Product->save()#6  /home/wordpress/public_html/wp-content/plugins/woocommerce/includes/admin/class-wc-admin-duplicate-product.php(116): WC_Admin_Duplicate_Product->product_duplicate()#7  /home/wordpress/public_html/wp-includes/class-wp-hook.php(341): WC_Admin_Duplicate_Product->duplicate_product_action()#8  /home/wordpress/public_html/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters()#9  /home/wordpress/public_html/wp-includes/plugin.php(522): WP_Hook->do_action()#10  /home/wordpress/public_html/wp-admin/admin.php(424): do_action()#11  /home/wordpress/public_html/wp-admin/edit.php(10): require_once(' /home/wordpress/...')#12 {main}  thrown in  /home/wordpress/public_html/wp-content/plugins/woocommerce/src/Internal/Caches/VersionStringGenerator.php on line 155
       ```
   
 * For debugging the issue, we disabled all other plugins except WooCommerce, the
   duplicate page plugin (for testing) and LS-Cache and the crit. error still occurred.
   The only way to fix that crit. error sofar, is renaming the object-cache.php 
   to object-cache.php.bak. Disabling the Object Cache in the LS Cache Settings 
   page did not solve the issue as well.
 * Regards,
 * JT
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fphp-fatal-error-uncaught-typeerror-19%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

Viewing 1 replies (of 1 total)

 *  Plugin Support [litetim](https://wordpress.org/support/users/litetim/)
 * (@litetim)
 * [3 months, 3 weeks ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-typeerror-19/#post-18827554)
 * [@jannis01](https://wordpress.org/support/users/jannis01/) please make sure your**
   Object cache** connection is setup correctly.
   **Null** if returned by LSC when
   OC is ON but connection is not working as expected.

Viewing 1 replies (of 1 total)

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 * Last activity: [3 months, 3 weeks ago](https://wordpress.org/support/topic/php-fatal-error-uncaught-typeerror-19/#post-18827554)
 * Status: resolved