Are you able to open the workbook in Tableau desktop and connect to the data source and render the views? The error indicates a problem connecting to the data source. If the view renders and data connectivity is fine in Tableau Desktop, I suggest republishing the view to Server and verifying data connectivity on the server with a refresh after this is complete.
Here are a few references that may assist:
If you continue to receive this error and can not determine the cause. Please contact tableau support at https://support.tableau.com