I have the EXACT same problem. All worked fine, till the plugin upgraded from 4.0.6 to 4.1.x. Even the latest 4.1.2. still causes this PHP Fatal error:
Got error ‘PHP message: PHP Warning: array_replace_recursive(): Expected parameter 2 to be an array, string given in /home/username/www/www.website.com/wp-content/plugins/woocommerce-myparcel/includes/admin/settings/class-wcmp-settings-data.php on line 168’, referer: https://www.website.com/wp-admin/admin.php?page=w3tc_dashboard&w3tc_note=flush_all
Rolling back to 4.0.6 immediately fixed it.
Please look deeper into what is causing this.
The site uses a country, but whatever the user enters, the plugin cannot figure out the address and does not calculate a fee.
