Instance upgrade from Helsinki could cause large number of Group Alerts in Event Management
When Helsinki instance is upgraded to later versions such as Jakarta or Istanbul, large number of new group alerts in em_alert table are generated during upgrade.This may trigger lots of email notifications if email notifications were configured for new alerts.
From Istanbul version, alert groups are represented by virtual alerts (Source=Group Alert). Before the Istanbul version, alert groups were not in the em_alert table, they were in a different table. During the upgrade from Helsinki to Istanbul, these alert groups were moved to em_alert table - a new virtual alert was created for a alert group. Hence, lots of virtual alerts (Source=Group Alert) would be generated during upgrade process.
As a result the member alerts in a alert group got 'role in group' field updated (to Secondary) when the virtual alert (primary alert in the group) is created.
The issue may occur during the instance upgrade which includes source code changes and tables transitions. The solution is to close all the new virtual alerts generated during upgrade as it should not reoccur after the upgrade.