Flows in Tableau Server fails with error 'Failed to connect to "". In the Connections tab, click Edit to check the required fields and credentials, then try again'

Issue

Flows in Tableau Server fails with error:

'Failed to connect to "". In the Connections tab, click Edit to check the required fields and credentials, then try again'

Environment

Tableau Server 2021.3.1
JDBC

Resolution

Follow the steps below to install the driver:

1. Download jdbc and taco connector file.
If it is partner-built connector and available on Tableau Exchange it can be downloaded from https://extensiongallery.tableau.com/
For example, Amazon documentDB jdbc and taco file can be downloaded from here:
Amazon DocumentDB JDBC Driver v1.2.4

2. Copy jdbc driver to below directories:

For Tableau Desktop and Tableau Prep Builder:
   Windows: C:\Program Files\Tableau\Drivers
   macOS: /Users/[user]/Library/Tableau/Drivers

For Tableau Prep Conductor and workbook connections in Tableau Server all nodes:
   Window: C:\Program Files\Tableau\Drivers
   Linux: /opt/tableau/tableau_driver/jdbc

3. Copy taco file to below directories:

For Tableau Desktop:
   Windows: C:\Users[Windows User]\Documents\My Tableau Repository\Connectors
   macOS: /Users/[user]/Documents/My Tableau Repository/Connectors

For Tableau Prep Builder:
   Windows: C:\Users\[Windows User]\Documents\My Tableau Prep Repository\Connectors
   MacOS: /Users//Documents/My Tableau Prep Repository/Connectors

For Tableau Server older than 2021.2 copy the connector to the following directories in all nodes:
   [Tableau_Server_Installation_Directory]/data/tabsvc/vizqlserver/Connectors/
   [Tableau_Server_Installation_Directory]/data/tabsvc/flowprocessor/Connectors/
   [Tableau_Server_Installation_Directory]/data/tabsvc/flowqueryservice/Connectors/ (if directory exists)
   [Tableau_Server_Installation_Directory]/data/tabsvc/flowminerva/Connectors/ (if directory exists)

For Tableau Server 2021.2 or newer, copy to the following directory in all nodes and it will be automatically picked up by all Tableau Server processes:
  Windows: C:\Program Files\Tableau\Connectors
Linux: /opt/tableau/connectors

4. Restart Tableau Server.

Cause

Driver has not been configured completely.

Additional Information

The instructions are for flows that use data source connector that has been built with the Tableau Connector SDK (for example Amazon DocumentDB data source)
The issue does not happen with extract data source.

[BUG] Can't run Prep flow on Tableau Server #936
Connectors Built with the Tableau Connector SDK
Tableau Exchange >Amazon DocumentDB