'ERROR [08001] [Qlik][socket error] (439) WSA E HostUnreach: The Teradata server can't currently be reached over this network'

[AkashPohare_HB]

Hello Community,

Last week we have upgraded the Qlik Sense to May 2024 Patch 4 from Nov 2022 Patch 1.

While upgrading the we got few issues and had to repair the installation.

Since then we are facing an issue with the native Teradata connections in the new version. The screenshot of the error message from HUB is attached.

And below is the error message found in the connector logs:

TestConnect was not successful: message='Error message:  Please check the values for Username‚ Password‚ Host and other properties. Description: Client unable to establish connection', detailMessage='ERROR [08001] [Qlik][socket error] (439) WSA E HostUnreach: The Teradata server can't currently be reached over this network'.  

The Teradata database has a NLB(Network Load Balancer) in front and if we specify the host of NLB, we are getting the issue. The same setup used to work before the upgrade.

However, if we provide the DB hostname directly, then the connection works fine. However, as per policy we cant specify the DB hostname directly and needs to use NLB.

Kindly suggest how can this be fixed.

Thanks.

[diegozecchini]

Hi! here are a few troubleshooting steps I would try

Firstly check network configuration, trying to verify if the NLB (Network Load Balancer) is reachable from the Qlik Sense server. Use network tools (e.g., ping, tracert, telnet, or nc) to check if the NLB's hostname/IP is accessible from the Qlik Sense server. If the NLB is unreachable, check firewall settings and network policies to ensure access is permitted.
Then confirm that the Qlik Sense server can resolve the NLB's hostname correctly. Use the nslookup command to ensure the hostname resolves to the correct IP address. Misconfiguration in DNS could cause the host to be unreachable.

Since the setup worked before the upgrade, it’s possible that new security policies, firewall rules, or antivirus software on the Qlik Sense server are blocking connections to the NLB. Check the firewall rules and any recent network security changes.
Ensure that the ports required for Teradata (typically port 1025, 1026 for Teradata Database Manager) are open on the network and NLB.

Review the Qlik Sense data connection settings for the Teradata connector. Verify that the settings (e.g., username, password, host, port) are correctly specified.
Check if there are any new configurations required in the updated Qlik Sense version to connect via NLB.

Since connecting directly to the DB hostname works, there might be an issue with the NLB's configuration. Ensure that the NLB is correctly configured to forward traffic to the Teradata database and that no changes were made during the upgrade.
Review the health check settings on the NLB to ensure it's monitoring the Teradata database's correct ports.
The error logs indicate a socket error (439) suggesting a network communication failure. Investigate the Teradata connector logs for more detailed error information. Look for changes in how the connector communicates with Teradata in the latest Qlik Sense version.

As a last resort, even if I don't like I would go for a rollback.

[Anonymous]

Hello, as starting point, I believe you need to share a detailed tcpdump (or equivalent) from your NLB when you are trying to replicate the issue; depending on the load balancing technique - Network Address Translation, Direct Routing, ... - you might need to involve one or more interfaces; if DR is used as load balancing technique, I believe you also want to share a detailed tcpdump from your client.

Also, sharing the route tables of those hosts will certainly help.

[AkashPohare_HB]

Thanks for your time and inputs.

Unfortunately rollback is not an option for me as the new version offers many good features.

When i ping the NLB DNS from the Qlik Sense server, it says Unable to resolve the hostname. However, even before Qlik Sense upgrade, the ping resulted the same output and still connection used to work.

Now, after upgrade as well the ping to the NLB DNS gives same output, but the connection from Qlik Sense HUB fails and works only if the DB hostname is provided explicitly.

The port connectivity works if tested between Qlik Server and DB server instead of the NLB DNS, however same was the case before the upgrade.

I can see that the Qlik Teradata connector has been upgraded and causing the issue.

[ADRANGI]

Hi AkashPohare_HB,

Did you manage to resolve the issue with the Teradata connection, If so can you please mention how you have resolved it ?

[diegozecchini]

Hi!
Since ping to the NLB DNS never worked even before the upgrade, check if nslookup resolves the hostname correctly:

nslookup <NLB_HOSTNAME>
If this fails, Qlik Sense might be relying on cached or alternative resolution methods in the previous version.

Try testing the connection from Qlik Sense with an explicit IP instead of a hostname (even if it’s against policy, just for debugging):

telnet <NLB_IP> <TERADATA_PORT>
If the IP works but the hostname doesn’t, then it's a DNS issue..

I suggest also to use DBeaver or a simple ODBC test client to connect to Teradata via NLB to confirm if the issue is specific to Qlik.

[AkashPohare_HB]

Hello @ADRANGI ,

If you are using NLB in front of Teradata servers, the connection from native Qlik Teradata connectors is failing. However, you can specify the hostname of one of the Teradata servers for the connection or else you can use Teradata ODBC driver where you can create connection using with NLB hostname or server hostname. Currently, I have created a connection using NLB hostname through ODBC drivers and it works fine.

I had raised case to Qlik to fix the issue with Qlik connector, still no luck.

Hope this helps.

Thanks.

[ADRANGI]

Thanks @AkashPohare_HB 

We will try establishing a connection using a driver.

[sujeet_shirude]

@AkashPohare_HB We recently upgraded our Qlik Sense environment from Nov 2023 SR9 to May 2025 SR3 version and we are getting same error. What did you do to resolve this issue? Any insights you can provide would be helpful. Thank you in advance! @Sonja_Bauernfeind 

[AkashPohare_HB]

@sujeet_shirude  issue is still not fixed, however we are using the workaround here. Earlier we used to pass NLB's hostname and now we are directly passing one of the DB's hostname. Also, if you can use ODBC driver, it works. This is clearly issue with Qlik Sense, however we did not get any fix even though we had raised case with Qlik.