Paused scheduled jobs restarted after upgrade

Scenario:

After upgrading to version 7.9.2 or higher from 7.5.1 or lower you noticed that jobs that were previously paused are now resumed and running. JasperServer jobs are all running successfully but some older jobs changed their status to Running when they shouldn't

Solution:

The issue may appear when you run upgrade-samedb from previous version to the newer one. Check the records qrtz_simple_trigger and qrtz_trigger in your repository database for Instance Name field. You should see same jobs repeating under different instance names quartzScheduler and JasperServerScheduler. If that's the case, you can try to rename the:
org.quartz.scheduler.instanceName=JasperServerScheduler
to
org.quartz.scheduler.instanceName=quartzScheduler

in js.quartz.base.properties file.

This will switch the scheduler to run all jobs as defined under quartzScheduler triggers and not create new JasperServerScheduler-owned triggers. Since you already have all the original quartzScheduler triggers in place this would ensure that all the old job configs will be used. The only issue is that some old jobs will be considered misfired and they will handle misfiring accordingly to the misfire policy set. This approach won't require you to modify any existing records in the DB, too.