If you're also seeing 'localhost' in the External data URL part of the message, then the correct solution to the problem is not likely the one that was posted in this thread, but your HTTP / HTTPS Entry URL parameters for the Application tab in the CSA are either blank or incorrectly contain localhost.
Those parameters should be populated with the normal URL that all users use to access the application, e.g., if you are normally navigating around Clarity with URLs like this:
https://yourserver.com/niku/nu#action:mainnav.work
You would put this in your Entry URL fields of the CSA:
https://yourserver.com
If you are using a non-default port and it's included in your URLs normally like this:
https://yourserver.com:12345/niku/nu#action:mainnav.work
Then you would populate your Entry URL fields like this instead:
https://yourserver.com:12345
You may need to restart the Clarity app services after saving these changes in the CSA when you are able to do so before they will be picked up (depending on caches and other settings).