Lost connection to server, Reconnecting or Session Lost when accessing QlikView documents
Opening or navigating a QlikView application with the Full Browser client leads to "Lost Connection, Reconnecting." or "Session Lost". This is often caused by large documents or complex calculations that take longer then the configured timeout.
The same behaviour is not seen when using the Internet Explorer plugin. The problem can occur for both the QlikViewWebServer and MicrosoftIIS.
This issue may happen if the document contains complex formulas/calculations, or the data set is too large for the standard timeout. The Internet Explorer plugin communicates directly with the QlikView Server, while the Full Browser Client (AJAX) communicates with the web server first. Different timeout values apply. QlikView WebServer, as well as Microsoft IIS, have a timeout value which at a default of 60 seconds.
There are different timeout values that can be adjusted to allow the webserver to wait for a return from the QlikView server longer, as well as to allow calculations more time to complete. Keep in mind that it is recommended to tune these settings to an appropriate level based on your environment. The settings used in the examples below are based on very large applications.
Increase QvsTimeout value.
Stop the QlikView WebServer Service
Navigate to %ProgramData%\QlikTech\WebServer
Change <QvsTimeout>60</QvsTimeout> accordingly
Save the file, and start the QlikView WebServer Service
For QlikView November 2017 SR1 and above: Release notes attached for QV 12.20 SR1