The Oracle Database 12.1 parameter OPTIMIZER_ADAPTIVE_FEATURES has been made OBSOLETE (i.e. must be removed from the SPFILE when upgrading) in Oracle Database 12.2.
It gets replaced with two parameters of whom one is enabled, the other one is disabled by default:
https://mikedietrichde.com/2016/11/22/optimizer_adaptive_features-obsolete-in-oracle-12-2/
The Oracle Database 12.1 parameter OPTIMIZER_ADAPTIVE_FEATURES has been made OBSOLETE (i.e. must be removed from the SPFILE when upgrading) in Oracle Database 12.2.
It gets replaced with two parameters of whom one is enabled, the other one is disabled by default:
https://blogs.oracle.com/optimizer/optimizer-adaptive-features-in-oracle-database-12c-release-2
Josselin Joly