Same error on my website appeared a week ago last Thursday.
As my site has been using this plugin for over two years successfully integrated with the Transdirect plugin I’ve diagnosed the WordPress version as possible cause. Currently on 5.0 need to downgrade to 5.6 if anyone has tried this please reply as Transdirect seem to have dropped further development on what should be a must have plugin.
I’ve had to turn it off to prevent customers all getting free freight and have been searching for a better plugin. Rob. https://Www.midwaymowers.com.au
