Unable to configure Square Payment Extension

We are getting this message on OC 2.3.0.2 dashboard when we are trying to connect to Square.

"We detected a possible cross site attack and have terminated your connection attempt. Please verify your application ID and secret and try again using the buttons in the admin panel."

Any pointers will be helpful.

Thank you.

This error is provided by OC, fortunately whenever the case applies with Squareup regarding XSS vulnerabilities with random URLs. In this case, you are either missing the state, code or might be using an invalid / no longer valid API account.