Verify if any of dependent data sources of the protected data source %DatasourceName; were removed or got moved from one ...

Verify if any of dependent data sources of the protected data source %DatasourceName; were removed or got moved from one server to another. If either of this has happened, then on the Protection pane, stop protection for this data source, and select the "Retain current data backups" option. Then recreate the protection group %DatasourceName; again.