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May 10, 2022 3:17:46 PM
Jan 25, 2021 9:44:39 PM
By accessing the tenant of the Qlik Sense SaaS editions, you may get the following error after trying to open an app.
"Unable to connect to the Qlik Sense engine. Possible causes: too many connections, the service is offline, or networking issues."
Environment
- Qlik Sense Enterprise SaaS
- Qlik Sense Business
Resolution
In the most common scenario, the error is related to an idle session timeout. If the error occurs after 20 min idle time, the only required action is to click "Refresh" in order to reconnect the client to Qlik Sense.
For this scenario, a more user-friendly message is planned for future Qlik Cloud releases.
It is recommended to try and establish if a network device between the browser and the Internet is causing the connection error if it occurs immediately or sooner than idle session timeout.
- Contact your local IT helpdesk for troubleshooting and advice.
- Confirm that network components support Websocket connections to your tenant <tenantname>.<region>.qlikcloud.com
- Check if the device utilizes an Internet proxy for Internet access
- Disable VPN if feasible
-
Connect to Qlik Cloud tenant from a different device or network
- Connect with a non-corporate device, to quickly identify if corporate policy is causing the issue
- Access Qlik Download page as a test, if the tenant is not allowed from another device
-
Check browser dev tools for more specific error messages
- Search Qlik Support Knowledge for related articles and known issues
- Open Qlik Support ticket if the error can not be resolved and local IT can not find a root cause
Cause
Qlik Sense uses WebSockets that enable communication between the web browser and Qlik Sense server. A Qlik Sense application gets generated with visualization objects and data via this communication.
The same technology is applied for web integration where Qlik Sense objects are embedded in other pages.
The root cause of this error is that the browser's WebSocket connection has been terminated for various reasons;
- The most common scenario is that the session has been idle for 20 minutes, and session timeout has been reached in Qlik Sense engine. In such a case, the session will be restored by pressing "Refresh" in the error dialog.
- The WebSocket connection may be terminated prematurely or blocked by a network device.
- If the error occurs immediately when an app is accessed, it may indicate that WebSocket traffic is not allowed to pass through from the browser to the Internet.
It may also indicate that multiple concurrent WebSocket connections are not allowed in all network devices between the browser and the Internet. - If the error occurs a few seconds after the app has been successfully opened, it may indicate that the WebSocket connection is not allowed to be persistent in the network devices between the browser and the Internet.
Qlik Sense requires persistent WebSocket connections, and also sends TCP keep-alive packages every ~30 secs to keep the connection open even when a user is not actively interacting with a Qlik Sense app. This keep-alive mechanism will not work if a network device has a lower connection timeout than 30 seconds. - WebSocket connections use a different (WSS) protocol and port than normal (HTTPS) web traffic. Network devices between the browser and the Internet must support the use of the WebSocket protocol.
- If the error occurs immediately when an app is accessed, it may indicate that WebSocket traffic is not allowed to pass through from the browser to the Internet.
