During promotion to CSRS, we first restart the secondaries with --configsvr and --replicaSetConfigShardMaintenanceMode. As soon as the secondaries are restarted with these flags, they will start attaching --configsvr to their hello replies and expecting their fellow replica set members to do the same. This expectation can cause issues once one of these nodes steps up to primary as it may contact a secondary that was not yet restarted and thus is not including the --configsvr field in hello replies.