After upgrading Oracle Grid Infrastructure, upgrade the Enterprise Manager Cloud Control target.
Because Oracle Grid Infrastructure 18c is an out-of-place upgrade of the Oracle Clusterware home in a new location (the Oracle Grid Infrastructure for a cluster home, or Grid home), the path for the
CRS_HOME parameter in some parameter files must be changed. If you do not change the parameter, then you encounter errors such as "cluster target broken" on Oracle Enterprise Manager Cloud Control.
To resolve the issue, update the Enterprise Manager Cloud Control target, and then update the Enterprise Manager Agent Base Directory on each cluster member node running an agent.