What is the expected behaviour, but what actually happens?
When did it start happening?
Where in the system is the error seen? (Client side, Server side...)
When is it triggered, what user action/system action causes it? (Trigger reload, user clicks on an object in a document...)
What parts of the environment are included in the problem (End user and direct document on client / end user through reverse proxy or load balancer to Qlik WebServer / etc..)
Gather the relevant log and har files, comparing those showing the issue and those without. (ex. successful reload and unsuccessful reload of the same document). For log file locations, please see the individual product documentation.
To move on to Step 2, the following is necessary:
Clear understanding of the symptoms
Clear picture of the error with a clearly displayed message
Correct log and har files are gathered and reviewed to find additional error messages not displayed directly to the end user
In case of configuration problems, ensure that the setup follows the recommendations and best practices listed there. Example for multi-node environments include "Do we have all the necessary ports open?" A list for those can be found on our Help.
Third-Party Vendors / Resources
Important if 3rd party software is interacting with the Qlik software and included. Example in case of the problem is only seen if a Reverse Proxy is in play, and the symptoms indicate that QlikSense is unable to establish a Websocket. Double check if the 3rd party proxy is compatible with WebSockets and/or correctly configured.
Additional troubleshooting articles for the specific products and most common issues can be found in the Qlik Article Database. Below are a few useful links (Portal access may be required).