Qlik Sense Applications Showing Different Data on Different Nodes

After upgrading to Qlik Sense September 2018 reloads do not result in the app being updated on all nodes in the same Qlik Sense site. Intermittently old data remains in the Qlik Sense Engine cache on some nodes, causing the node to return outdated data to accessing users. The symptom disappears when Qlik Sense Engine is restarted on the affected node. 

This issue is often associated with the below log traces:

• Look at Trace\System log there should be errors indicating problem saving something with an exception about which type of database entity it had issue saving.
• To find database connectivity issues look at Trace\Synchornization log and look for ERROR with stacktrace containing "PgSql" or "Devart" in the message.

• Look at Trace\System logs for the service and look for any GET exceptions with stack traces containing "Devart" or "PgSQL".
• Check the Trace\Synchronization log for the service for any notification Error messages, or even containing a "PgSql" or "Devart" in the stacktrace.