I was playing around in sandbox mode to see if I can finally get the customer bulk upsert operation to work. I made about 20 definitions and created a customer with an alpha-numeric first name. The red bars in the picture represent the correct API ID I use to access my sandbox. It doesn’t matter if I use the correct values or not, when I run the request in api explorer I get the 500 internal server error.
Until this is fixed and until I can figure out how it works, I’ll have to resort to adding one item at a time which would make the experience slow for a customer if he is buying tons of items.
What is your application ID? Please note what you have hidden in the image that you provided is your sandbox access token NOT the application ID. You should never share your access token however the application ID is safe to share.