If your system has recently been updated, you may need to create an Integration Settings record in order to access stored payment methods from PaySimple. If you see the following error: "There was an exception while getting stored payment method:PaySimple Endpoint Value is required from Integration Settings" follow this Article to resolve.
Navigate to Setup
Use the QuickFind to navigate to Custom Settings
choose Integration Settings
Click New at the top of the page. Note: DO NOT click the lower of the two New buttons on this page, please note the position of each.
Save the record
The PaySimple Endpoint Value will auto-populate in the record.