How to upgrade CEDR to DRS

I know the AWS Document to Upgrade from CEDR to DRS: https://docs.cloudendure.com/#Configuring_and_Running_Disaster_Recovery/Upgrade_CEDR_to_DRS/Upgrade_CEDR_to_DRS.htm#Upgrading_from_CEDR_to_AWS%C2%A0DRS%3FTocPath%3DNavigation%7CConfiguring%2520and%2520Running%2520Disaster%2520Recovery%7CUpgrading%2520from%2520CEDR%2520to%2520AWS%25C2%25A0DRS%7C_____0

However after upgrading to DRS, unable to Start Reverse Replication:

I am performing Failback in AWS Cross Regions.

Please share the correct document or help me to resolve this error to move ahead. Your help is appreciated. Thank you.