The invalid redirect message generally only occurs if the redirect URI is different in the integration compared to the value listed in your Mashery account. If you are the developer of the integration then this is something that you can change on your own. If you did not develop the integration then you would need to reach out to the developer so they can make sure those values match.
I cannot speak to the requirement of having to upgrade to a different version of Goldmine in order to continue using it as Constant Contact did not create the integration. You may want to check on our Marketplace to see if there are any other alternate options for you.
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