When trying to migrate VPS in:
Top > Service Director > Virtuozzo Manager > VPSs > select VPS > Migrate >
choose destination node > Submit
Error is thrown:
Operation result Scheduling of Instance migration has failed. Reason: Migration task already exists.
There is an existing migration task for this VPS or Tasks for VPS migration were canceled through task manager but were not deleted from "Migration tasks"
Either rerun existing migration tasks or, if you want to discard previous migration and start a new one, delete task from "Migration tasks" screen: