Thanks for your answer.
Sure, the recommandation will be to contact TSC first/before the downgrade itself to get assistance and ensure the downgrade is the last solution.
Based on the documentation, if I'm understanding properly:
You can downgrade from... To...
ONTAP 9.1 ONTAP 9
Note: Downgrade of a two-node MetroCluster
configuration from ONTAP 9.1 to 9 is disruptive.
You must perform a revert from... To...
ONTAP 9.8 ONTAP 9.7
ONTAP 9.7 ONTAP 9.6
ONTAP 9.6 ONTAP 9.5
ONTAP 9.5 ONTAP 9.4
ONTAP 9.4 ONTAP 9.3
ONTAP 9.3 ONTAP 9.2
ONTAP 9.2 ONTAP 9.1
ONTAP 9.1 or ONTAP 9 Data ONTAP 8.3.x
So, that means we can only downgrade feature version by feature version. upgrade can be done 2 by 2 but not the downgrade?
At the end, customer wants to clarify and have something to present to the board in case of revert is needed.
And also, in other terms, that means the information in the upgrade plan are "inacurate" regarding versions?
Thanks again.