Java Error raised when loading older scenarios

[OFR-IIASA]

Code sample or context

loading and old scenario with the latest ixmp/message_ix version (on "ene_ixmp").

import message_ix
import ixmp
mp = ixmp.Platform()

scen = message_ix.Scenario(mp, 'MESSAGE-GLOBIOM CD-LINKS R2.3.1', 'NPi2020-con-prim-dir-ncr')

Expected result

loads message_ix.Scenario object

Problem description

RuntimeError: unhandled Java exception: No Set 'rating' exists in this Scenario!

Versions

ixmp/master
message_ix/master