FirstData is deprecating their use of LinkPoint API. They are suggesting AuthorizeNet (slightly modified) as a workaround.
According to their instructions for using AuthorizeNet.
https://firstdata.zendesk.com/entrie...n-Instructions
you have to give checkout_process as a page for them to call back to. But this page wasn't really ever meant to be loaded directly, so when it does load, it gives a cookie error (I believe what is happening is that init_includes/init_cart_handler.php sees that the session isn't started and throws an error).
This is independent of browser (happens in both Chrome and FF).
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