Newest forwarders compatibility with older version of Splunk Enterprise

[nessaner]

Hello, 
There is this old system where we want to upgrade splunk to the newest version
First we want to upgrade the forwarders on 3 test servers 
The current version of splunk universal forwarder is 7.0.3.0
We want to rise it to the 9.21
Would that version works for the time being with Splunk Enterprise 7.3.1?

I know it would be better first upgrade the enterprise, as best practice is to use indexers with versions that are the same or higher than forwarder versions. (but there is hesitation to upgrade indexers first, as it's used also for data from production)
But would it be possible to do forwarders first? 

[nessaner]

Hi, we decided to create backups and just go for it.
It worked fine! After upgrade everything is indexing without any issues. Also no problem during upgrade from msi.
Thanks for giving us a little courage I guess. We decided to "experiment". For the greater good heh.

[richgalloway · Accepted solution]

Yes, it is possible to upgrade forwarders first.  As you've noted, that is contrary to the published procedures and may not work.  Also, Splunk version 7.3.1 is well outdated so there is no guidance about its compatibility with other versions.

This will be an interesting experiment.  Please let us know how it goes.