how can i downgrade PRTG version from 12.3.2.268 to 9.2.1.2280 without any data loss?

Hello,

we strongly advise against such a downgrade to be honest. It's potentially very tricky and will very likely mean data loss. Please be aware though that you might need to "downgrade" any Remote Probes manually again, by downloading the Remote Probe installer then from your very own PRTG after the "downgrade to 9", because version 12 that you are currently running is of course newer than the 9 (so Probes will not automatically downgrade themselves). Furthermore, if you added any sensors that are only available with the version 12 (but not in 9), those will not work any more after the switch back to 9. And in case you are running the cluster, that would make things much more complicated I'm afraid. It would be necessary then to:

• Stop the PRTG Services on the Failover Node
• Do the downgrade on the Master node.
• Then do manually downgrade the Failover Node as well (with the PRTG Service still stopped when you start the installer for PRTG 9)
• After a few minutes of the Cluster running, please check if the Failover has the "same" configuration (all devices and sensors on the Cluster Probe) then

best regards