After disabling two step checkout in Service Portal user is receives error (Failing widget: 'SC Shopping Cart' )
This specific issue was seen in London patch 6, however, it may be seen in other versions.
Shopping cart widget, Checkout is triggering twice. Once creating the request correctly and then again passing a 'null' value.
Set the "Auto update cart" value and displayValue to false in the sc_cart page.
Steps for implementing:
Navigate to Service Portal Configurations > Select Page Editor > Select sc_cart page > Select "Instance 1" from the chart at the top > Scroll down to 'Additional options, JSON Format' field > Set the "Auto update cart" value and displayValue from 'true' to 'false'.