A common mistake of Unexpected error is the insertion of incorrect Request URL of the post request.
Below represents the Unexpected error:
"message": "Unexpected error occurred."
During integration testing process you might get “Unexpected error” to your post response. This is probably happening because of a typo in the “Request URL”. For example, the problem might occur when the URL is wrong.
Please refer to our API docs, section 1.2 URL “ https://docs.api.isignthis.com/identity-services-create-transaction/” for more information.