Hello,
I’ve tried deactivating all plugins but the issue still remains.
It’s not true because there is no problem with the cart if third-party plugins are deactivated
https://gyazo.com/43c634259523ef1853ffcdef8a72703e
And appears again once the Widget Disable plugin is enabled. So, contact the plugin author to fix the mentioned error and follow the instructions next time, please.
Regards