topic error in engine in Connectivity & Data Prep

error in engine

ireshaimali890 — Wed, 22 Apr 2026 09:15:42 GMT

Please help me the find out the root cause and the solution?

Re: error in engine

Eduardo_Monteiro — Wed, 22 Apr 2026 18:51:38 GMT

Hi @ireshaimali890

Can you please share more details for context?

How often does this happen?

Can you please share the logs %ProgramData%\Qlik\Sense\Log\Engine\System\

Did you check if services are running (Engine, Proxy and Repository)?

Please check the following article: Unable to connect to the Qlik Sense engine error d... - Qlik Community - 1717211

Regards,

Re: error in engine

Greg_Taffer — Thu, 23 Apr 2026 20:34:56 GMT

Unable to connect to the Qlik Sense engine is commonly caused by idle session timeouts (20+ minutes), blocked WebSocket traffic, or stopped Qlik Sense services. Other factors include network device timeouts, misconfigured virtual proxies, or expired security certificates. Immediate fixes include refreshing the browser, checking service status, or white-listing IP addresses in the QMC.

Key Reasons for Qlik Sense Engine Connection Errors

Session Timeout: The session has been idle for over 20 minutes in Qlik Cloud or the configured time in Enterprise, requiring a simple refresh.
WebSocket Issues: WebSocket (WSS) traffic is blocked between the browser and server, or network devices do not support persistent WebSocket connections.
Stopped Services: The Qlik Sense Engine Service (QES) or Proxy Service (QPS) is not running on the server.
Network/Proxy Interference: A firewall or proxy server is terminating the connection before the 30-second keep-alive packets can work.
Incorrect Host White Listing: The Virtual Proxy is not configured with the correct WebSocket host whitelist, especially when using custom DNS or load balancers.
Security Certificate Issues: Expired, invalid, or misconfigured SSL/TLS certificates on the Qlik Sense server.
Resource Exhaustion: Too many concurrent connections, exceeding the postgresql.conf maximum, or high memory usage on the server.

Troubleshooting Steps

Restart Services: Verify in QMC that Engines are running and restart the Engine/Dispatcher services.
Check Browser Console: Review browser developer tools (F12) for detailed WebSocket connection failures.
Refresh/Reconnect: Simply refreshing the hub can resolve timeout issues.
White-list IPs: Add the server's IP address and hostnames to the virtual proxy whitelist.
Check Network/VPN: Disable VPNs and ensure firewalls allow WSS traffic.
Verify Certificates: Ensure root.cer is installed and valid.

For detailed diagnostics, use the Qlik log collector.

Re: error in engine

ireshaimali890 — Fri, 24 Apr 2026 03:43:41 GMT

This is occurring every day. Could you please let me know the solution for this? Is this happening due to heavy calculations in the app, or is it related to on premise RAM or a hardware performance issue?

Re: error in engine

Eduardo_Monteiro — Fri, 24 Apr 2026 04:07:29 GMT

Hi @ireshaimali890 -

The information you provided is too short to determine the root cause.

Please collect 2 days of logs and share, and I'll be able to help more efficiently.

Here's how to collect logs: How To Collect Log Files From Qlik Sense Enterpris... - Qlik Community -

1713168

Regards,