Qlik Sense - An error ocurred - Connection lost.

[denismarcio]

Hi,

This is my first time posting on this community, so I apologize in advance if this isn't the right place for my question.

I’ve recently encountered an issue with Qlik Sense that we haven’t been able to resolve, and I would greatly appreciate any insights from the experienced members here.

We have a Qlik Sense Enterprise - Core based Site (8 core) environment. This environment produces hundreds of analytical dashboards for various clients, with no history of issues regarding its use.

A recently developed dashboard runs normally, but after a few minutes of inactivity, it displays the message: "An error occurred: Connection lost. Make sure that Qlik Sense is running properly. If your session has timed out due to inactivity, refresh to continue working." Attached is an image of the error message, with the text in Portuguese:

After this error occurs, all applied filters on the dashboard are lost, resulting in a significant loss of productivity.

Upon researching within the community, we found this article (https://community.qlik.com/t5/Official-Support-Articles/Enabling-TCP-Keep-Alive-Functionality-In-Qli...) that seemed promising. We adjusted the "WebSocketPingInterval" key to 100 and 60, but there were no effective results—the error persists.

<add key="WebSocketPingInterval" value="100"/>
<add key="WebSocketPingInterval" value="60"/>

Any advice on what to do next?

[Or]

A few questions to perhaps help pinpoint the issue...

Does this always happen a certain exact period of inactivity?

Does it ever happen during active use?

Does it happen no matter where the application is opened (Your site, customer site, multiple computers)?

If you Binary Load the application into a new application, does the new one have the same issue?

[denismarcio]

Hello. Here are the responses:

Does this always happen a certain exact period of inactivity?
Yes, this always happens during a period of inactivity, but the time it takes to occur is not always the same (it varies from 3 to 25 minutes).

Does it ever happen during active use?
Yes, this does occur during active use, but only when the user stops interacting with the panel.

Does it happen no matter where the application is opened (Your site, customer site, multiple computers)?
Yes, this occurs regardless of where the panel is accessed. We have tested it both on the client's site and on our own site, and it happens on multiple computers

If you Binary Load the application into a new application, does the new one have the same issue?
We haven't tried that approach yet. We will do it today.

[Or]

In addition to testing the Binary Load approach (or even creating a fresh app with the same configuration to isolate whether it's the app itself or something else), I would suggest checking the relevant logs (Sessions, probably) for any relevant information, possibly with increased logging levels if required. I'd also suggest leaving the browser console open (typically F12) to see if any interesting messages pop up when the disconnect happens.

[denismarcio]

Or,

Thank you very much for your contributions.

We have updated a server to the latest version of Qlik Sense (the previously used version was February 2023), adjusted the WebSocketPingInterval settings to 120, and, after several tests, we concluded that the issue might be related to the client's proxy environment. Outside of this environment, no error messages occurred.

They will make adjustments to the proxy, and we will conduct new tests. We will report the results here.