Data 360: Error while creating new Data Action Target

Please follow the steps below to resolve the issue:

1. Ensure that the email template configured in Marketing Cloud includes an Unsubscribe option, as this is mandatory.
2. Validate the email template in Marketing Cloud by navigating to MC → Sends → Preview and Test.
3. Verify the Marketing Cloud Engagement (MCE) connection to ensure it is active, and confirm that no recent changes have been made to the API user credentials.
4. When using Email as the destination in a Data Action Target, ensure the email content is in basic HTML format only, without personalization or any code that retrieves attributes from a Data Extension.
5. If you are using a dynamic email template (for example, with AMPscript or content blocks dependent on Data Extension attributes), select Journey Builder API Event as the destination instead.

If the issue persists after completing the above steps, please raise a case with Salesforce Support for further investigation.