Method to downgrade to version 3.93 after upgrading WooCommerce 4 causes database errors

Today, after upgrading a client's WooCommerce to 4.0.1, a database error occurred, prompting issues like >save_action(Object(ActionScheduler_Action), NULL) #1. Based on feedback from other users on the official forum, the cause of this problem is typically having too many products (usually over 1000).The solution is to temporarily downgrade to WooCommerce 3.9.3 and wait for the next WooCommerce update to test if this bug is fixed.Downgrade method:1. Download the old versionWooCommerce 3.9.3 installation package2. Overwrite the files in the existing WooCommerce Plugin folder. 3. Restore the backed-up database. Reference: https://wordpress.org/support/topic/can-not-update-my-database/