Error "The 'firebird' data source does not support custom sql" Publishing or Accessing Published Workbooks Using Custom SQL with Firebird

Published: 20 May 2019
Last Modified Date: 22 May 2019


When opening a published workbook connected to Firebird using Custom SQL, the following error occurs:

TableauException: The 'firebird' data source does not support custom sql

Additionally, when publishing a Firebird connection using Custom SQL from Tableau Desktop, one of the following errors may occur:

Unknown server error
An unexpected error has occurred. If you continue to receive this error, contact your Tableau Server administrator.
SessionID <session>
TableauException: The 'firebird' data source does not support custom sql.
Do you want to reset the view?


An error occurred while communication with Tableau Server. The connection to the data sources might have been lost.
Error: Unable to connect to this Tableau Server data source.
The data source 'firebird' does not support custom sql.
Unable to connect to the server [""]. Check that the server is running and that you have access privileges to the requested database.


  • Tableau Online 
  • Tableau Desktop 
  • Firebird
  • Custom SQL


As a workaround, 
Work with your database administrator create a custom table view in the database using the same Custom SQL which was previously used in the Tableau Desktop workbook. Then connect to the custom table view from Tableau Desktop, and publish the data source as needed. 


Tableau no longer supports Custom SQL for Firebird, as Firebird is more vulnerable to security attacks when using Custom SQL. 

Additional Information

The Convert to custom SQL option in the Tableau Desktop Tables pane and the Data drop-down menu will be removed from Firebird connections in future releases.
Did this article resolve the issue?