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Also see a related video posted on Hub access times out with: Error Connection lost. Make sure that Qlik Sense is running properly
This option is available in Qlik Sense June 2018 Patch 1 and later releases.
Description of related problem:
Getting errors "Connection to the Qlik Sense engine failed for unspecified reasons. Refresh your browser or contact our system administrator" for external users on other browsers except for IE when they open the Qlik sense app and leave it inactive until it exceeds the Firewall session idle timeout. This is followed by a connection reset for the TCP WebSocket session.
For Qlik Sense Enterprise for Business (Cloud), see Loading of an app is hanging when using QlikSense Cloud.
TCP WebSocket connection is terminated by the firewall because the firewall is not receiving any TCP traffic such as keep-alive packets from client browser (e.g. Firefox, older Chrome versions). Specific web browsers have their own tcp keep-alive behavior.
This issue may be found with less frequency with IE because it sends the TCP Websocket keep-alive more frequent than any other main stream browser. Here are the default intervals for the three main browsers latest releases as of September 2020:
Default TCP-Keep-Alive intervals:
This functionality is by default switched off not to affect any existing customers. Customers who do not experience any issues with web sockets terminated by the network due to inactive SHOULD NOT switch this feature ON since it will send unnecessary traffic on the network. See How are WebSockets used in QlikSense ? for more information.
Where value is a suitable positive number depending on the inactive web socket timeout setting in the network. The effective interval that the Qlik Sense Proxy server will send keep-alive messages towards the client my oscillate between 2 x value and 1 x value, since it also takes into account backend inter-process socket activity. Eg: setting the value of WebSocketPingInterval to 30 may lead to keep-alive messages sent to the client every 30 or 60 seconds.
<add key="WebSocketPingInterval" value="0"/> <!-- Interval in seconds for the web socket ping to the client (a value of "0" is disabling the ping)–>
It is possible that the same WebSocketPingInterval value has different behaviors in each Qlik Sense Hub section due to various network device. The value may keep the connection live in Dashboard but still lose connection in Data Load Editor. You may test with a lower WebSocketPingInterval value until the proper value is found to keep connection in all sections. For example, when connecting CloudFlare as web application firewall, the WebSocketPingInterval value may need to set to 10 seconds otherwise "connection lost" may still be received in Data Load Editor even the rest of Qlik Sense Hub keeps connected.
4. Restart the Qlik Sense Proxy Service.
After performing the step 1-4 mentioned above, how to validate the thing for which have performed those step. Or how to identify that NPrinting server is connecting to Qliksense server
@RajanKasbe_Expo , are you performing this task to troubleshoot the connection setup on the NPrinting server? It is not clear how this post would assist with that task.
TCP Keep alive packets are sent to the server as long as you have an app open in Hub. These packets will show in a network capture.
is there a similar feature for keep alive for Qlikview?
I found only the SocketTimeOutInSeconds Setting, which is not the same as a Ping interval.
Hello @john_oll !
No equivalent exists for QlikView, as QlikView does not have that specific need. Extending the timeouts is generally sufficient, as we do not use WebSockets that will disconnect on inactivity.
However, third party tools (browsers, firewalls, proxies,..) can interfere here and cut the connection.
All the best,
If you have a multinode environment. On which server should this be done?
We have 4 hosting nodes (where our customers are connected to the HUB), 2 Proxy nodes, 3 reload nodes (engine nodes which reload apps daily) and the central node. Is this necessary on all nodes or just some?
Thanks and regards
This article is specifically aimed at the proxy service (hub connection), so any of the proxy nodes in your environment would need to have these changes made.
All the best,
I just changed the proxy config for our Proxy nodes and restartet the Services but it still disconnects after about 100s.
Shouldn't there now be visible Websocket requests which can be viewed in the browsers network traffic for the specific Qlik WS?
You would be seeing WebSocket traffic in your browser debug tools regardless of whether or not you've set this setting. Here is some general information on how to debug WebSocket traffic: Debugging WebSocket in Google Chrome.
Here's also one of ours: How to time a Qlik Sense WebSocket connection.
If your connection still times out, I'd recommend reviewing the relevant log files (not only Qlik Sense logs, but also your network components) to see where the connection is being terminated. Here is an article that walks through a few of the basics: Qlik Sense Enterprise Hub timeout.
Should you need more assistance, I'd recommend posting on our forums (Deployment and Management ) to get assistance from our larger community.
All the best,