Check Details
Check requirements: if the source database is a sharded instance, you need to disable the balancer in it before you can start migration.
Check description: an incremental migration task will get the oplog. If the balancer is enabled, moveChunk in the source database may cause data inconsistency in the target database.
Fix
1. Log in to the source database.
2. Run the following command to disable the source database balancer:
sh.stopBalancer()
sh.getBalancerState()
3. Run the verification task again.