This error usually happens, if WooCommerce’s Debugging has been activated. This is never a good idea to have activated on a live-setup because it slows down pages, and potentially shows error messages in the frontend.

The sync issue happens if WooCommerce encounters an error while generating the product-data for the import.

This can be solved by deactivating Debug Mode either through the plugin or directly in the WooCommerce files.

Using the Plugin #

If you are using Clerk.io’s v2.2.4 or later, Debugging can be disabled directly from the Plugin page in your WooCommerce backend.

Go to Clerk -> Clerk Settings -> Debug Guide and click Disable Debug Mode:

Or Directly in the Files #

Debug Mode can also be deactivated through FTP, in wp-config.php by setting define(WP_DEBUG’, false).

This guide explains it in more detail:

https://docs.woocommerce.com/document/woocommerce-product-search/api/debugging/

And this guide explains an alternate workaround:

https://aristath.github.io/blog/wp-hide-php-errors

Errors will still be logged even when not in Debug Mode, but they will be logged to a file instead.