Can't able to do MySQL engine version upgrade for the aurora global db cluster

I’m trying to perform a MySQL engine version upgrade for the aurora global db cluster from 5.7.mysql_aurora.2.07.2 to 5.7.mysql_aurora.2.09.2.
Provider version: 3.67
Terraform version: 0.12.31

But I’m facing this below issue:
InvalidGlobalClusterStateFault: Primary Cluster is upgrading or has pending upgrade: please retry the request once the primary cluster has finished the upgrade.

This is happening if the terraform tries to modify both primary and secondary at the same time. Not sure how to control them. This is kind of intermittent from my experience.

Any suggestion is, much appreciated.