DRAFT KB-XXXX "An error occurred while retrieving the report" in Task per Process Model report

Symptoms

When looking at the Task per Process Model report, the following error appears:

On the JBOSS_HOME/standalone/log/server.log file, this error is thrown:

2016-12-15 19:20:53,204 [ajp-/0.0.0.0:8009-4] ERROR com.appiancorp.process.analytics2.service.ProcessAnalyticsServiceFacade - com.appiancorp.kougar.driver.exceptions.Signal: index
2016-12-15 19:20:53,204 [ajp-/0.0.0.0:8009-4] ERROR com.appiancorp.process.analytics2.display.ProcessAnalyticsReportData - com.appiancorp.kougar.driver.exceptions.Signal: index
java.lang.RuntimeException: com.appiancorp.kougar.driver.exceptions.Signal: index

Cause

This issue can be caused by the fact that the Execution and Analytics engines are out of synchronization and need to be synchronized again.

Action

Resetting the Analytics Engines solves this issue. Refer to KB-1157 How to reset the analytics engines for on-premise installations of Appian for more details.

Affected Versions

This article applies to all versions of Appian.