JBO-29000: Unexpected exception caught: java.sql.SQLException, msg=ORA-20206: Target does not exist: : ORA-06512: at "SYSMAN.MGMT_TARGET"

JBO-29000: Unexpected exception caught: java.sql.SQLException,
msg=ORA-20206: Target does not exist: :
ORA-06512: at "SYSMAN.MGMT_TARGET", line 1228
ORA-06512: at "SYSMAN.EM_MONITORING", line 62

This is due to daylight Savings Time (DST) transition changes in Brazil.
EM 12c Agent was not running with the correct TZ after these DST changes to the time zone.

cd $AGENT_INST/bin

-- ./emctl stop agent
-- export TZ=Etc/GMT+3 <<<< This is the correct TZ after DST changes in the Brazil.
-- ./emctl resetTZ agent


Please Run the PLSQL which were printed by executing the above command on the repo database as SYSMAN and start the agent.

-- ./emctl start agent