Intermittent “Session Not Found” Error When Connecting to Published Data Source with Multi-Fact Relationship from Tableau Desktop

While connecting from Tableau Desktop to a published data source with multi-fact relationships on Tableau Server, we see a red exclamation mark next to a data source in Tableau Desktop if it is a PDS with a multi-fact relationship.

Version(s) Affected: 2024.x, 2025.x, 2026.x.

{"exception":"com.tableausoftware.vizdataservice.service.VizDataServiceException","description":"Session not found"}}} com.tableausoftware.vizdataservice.service.VizDataServiceException: Session not found

1. Prepare a three-node Tableau Server environment.
2. Deploy vizdataservice to node2 and node3 if it does not exist already.
3. Publish a data source with a multi-fact relationship to Tableau Server.
4. Connect to this PDS from Tableau Desktop and verify that it works without issues.
5. Deploy a new coordination service ensemble on node1 only.
6. Remove filestore from node2 and node3 if it exists.
7. (Optional) Save the topology settings by running the command "tsm settings export".
8. Remove node2 and node3 from the cluster.
9. Add two nodes back to the cluster. You can reuse the machines used for the original node2 and node3.
10. (Optional) Modify the file generated in step 7 by replacing "node2" and "node3" with "node4" and "node5", respectively.
11. (Optional) Import the topology settings by running the command "tsm settings import".
12. Make sure vizdataservice is deployed on the two new nodes, namely node4 and node5.
13. (Optional) Remove vizdataservice from node1.
14. Launch Tableau Desktop with the option "-DLogDetail=HTTPRequestor -DLogLevel=debug".
15. Connect to the PDS with a multi-fact relationship, and try to build a view. You may not notice any errors in the GUI.
16. Check Desktop log files, and you should see HTTP 404 errors for some /readMetadata and /executeQueries requests.
17. Check Desktop log files for "routing-id". You will see the value "2:0" or "3:0", rather than the correct "4:0" or "5:0".