"Could not communicate with vendor" error when adding an add-on
This error means Heroku is receiving an invalid response from the add-on partner when trying to add the add-on to your application. In order to assure that this error is not temporary, please wait a few minutes and then try this request again. You may also check the add-on partner's status site to see if they are currently managing an incident which might impact provisioning.
If this error persists, please open a support ticket and let us know which add-on you were trying to add. We'll connect you with the add-on partner to resolve the issue.